ds@1952: /*
ds@1952: ** 2001 September 15
ds@1952: **
ds@1952: ** The author disclaims copyright to this source code.  In place of
ds@1952: ** a legal notice, here is a blessing:
ds@1952: **
ds@1952: **    May you do good and not evil.
ds@1952: **    May you find forgiveness for yourself and forgive others.
ds@1952: **    May you share freely, never taking more than you give.
ds@1952: **
ds@1952: *************************************************************************
ds@1952: ** This file contains C code routines that are called by the parser
ds@1952: ** to handle SELECT statements in SQLite.
ds@1952: **
ds@1952: ** $Id$
ds@1952: */
ds@1952: #include "sqliteInt.h"
ds@1952: 
ds@1952: 
ds@1952: /*
ds@1952: ** Delete all the content of a Select structure but do not deallocate
ds@1952: ** the select structure itself.
ds@1952: */
ds@1952: static void clearSelect(Select *p){
ds@1952:   sqlite3ExprListDelete(p->pEList);
ds@1952:   sqlite3SrcListDelete(p->pSrc);
ds@1952:   sqlite3ExprDelete(p->pWhere);
ds@1952:   sqlite3ExprListDelete(p->pGroupBy);
ds@1952:   sqlite3ExprDelete(p->pHaving);
ds@1952:   sqlite3ExprListDelete(p->pOrderBy);
ds@1952:   sqlite3SelectDelete(p->pPrior);
ds@1952:   sqlite3ExprDelete(p->pLimit);
ds@1952:   sqlite3ExprDelete(p->pOffset);
ds@1952: }
ds@1952: 
ds@1952: 
ds@1952: /*
ds@1952: ** Allocate a new Select structure and return a pointer to that
ds@1952: ** structure.
ds@1952: */
ds@1952: Select *sqlite3SelectNew(
ds@1952:   Parse *pParse,        /* Parsing context */
ds@1952:   ExprList *pEList,     /* which columns to include in the result */
ds@1952:   SrcList *pSrc,        /* the FROM clause -- which tables to scan */
ds@1952:   Expr *pWhere,         /* the WHERE clause */
ds@1952:   ExprList *pGroupBy,   /* the GROUP BY clause */
ds@1952:   Expr *pHaving,        /* the HAVING clause */
ds@1952:   ExprList *pOrderBy,   /* the ORDER BY clause */
ds@1952:   int isDistinct,       /* true if the DISTINCT keyword is present */
ds@1952:   Expr *pLimit,         /* LIMIT value.  NULL means not used */
ds@1952:   Expr *pOffset         /* OFFSET value.  NULL means no offset */
ds@1952: ){
ds@1952:   Select *pNew;
ds@1952:   Select standin;
ds@1952:   sqlite3 *db = pParse->db;
ds@1952:   pNew = sqlite3DbMallocZero(db, sizeof(*pNew) );
ds@1952:   assert( !pOffset || pLimit );   /* Can't have OFFSET without LIMIT. */
ds@1952:   if( pNew==0 ){
ds@1952:     pNew = &standin;
ds@1952:     memset(pNew, 0, sizeof(*pNew));
ds@1952:   }
ds@1952:   if( pEList==0 ){
ds@1952:     pEList = sqlite3ExprListAppend(pParse, 0, sqlite3Expr(db,TK_ALL,0,0,0), 0);
ds@1952:   }
ds@1952:   pNew->pEList = pEList;
ds@1952:   pNew->pSrc = pSrc;
ds@1952:   pNew->pWhere = pWhere;
ds@1952:   pNew->pGroupBy = pGroupBy;
ds@1952:   pNew->pHaving = pHaving;
ds@1952:   pNew->pOrderBy = pOrderBy;
ds@1952:   pNew->isDistinct = isDistinct;
ds@1952:   pNew->op = TK_SELECT;
ds@1952:   assert( pOffset==0 || pLimit!=0 );
ds@1952:   pNew->pLimit = pLimit;
ds@1952:   pNew->pOffset = pOffset;
ds@1952:   pNew->iLimit = -1;
ds@1952:   pNew->iOffset = -1;
ds@1952:   pNew->addrOpenEphm[0] = -1;
ds@1952:   pNew->addrOpenEphm[1] = -1;
ds@1952:   pNew->addrOpenEphm[2] = -1;
ds@1952:   if( pNew==&standin) {
ds@1952:     clearSelect(pNew);
ds@1952:     pNew = 0;
ds@1952:   }
ds@1952:   return pNew;
ds@1952: }
ds@1952: 
ds@1952: /*
ds@1952: ** Delete the given Select structure and all of its substructures.
ds@1952: */
ds@1952: void sqlite3SelectDelete(Select *p){
ds@1952:   if( p ){
ds@1952:     clearSelect(p);
ds@1952:     sqlite3_free(p);
ds@1952:   }
ds@1952: }
ds@1952: 
ds@1952: /*
ds@1952: ** Given 1 to 3 identifiers preceeding the JOIN keyword, determine the
ds@1952: ** type of join.  Return an integer constant that expresses that type
ds@1952: ** in terms of the following bit values:
ds@1952: **
ds@1952: **     JT_INNER
ds@1952: **     JT_CROSS
ds@1952: **     JT_OUTER
ds@1952: **     JT_NATURAL
ds@1952: **     JT_LEFT
ds@1952: **     JT_RIGHT
ds@1952: **
ds@1952: ** A full outer join is the combination of JT_LEFT and JT_RIGHT.
ds@1952: **
ds@1952: ** If an illegal or unsupported join type is seen, then still return
ds@1952: ** a join type, but put an error in the pParse structure.
ds@1952: */
ds@1952: int sqlite3JoinType(Parse *pParse, Token *pA, Token *pB, Token *pC){
ds@1952:   int jointype = 0;
ds@1952:   Token *apAll[3];
ds@1952:   Token *p;
ds@1952:   static const struct {
ds@1952:     const char zKeyword[8];
ds@1952:     u8 nChar;
ds@1952:     u8 code;
ds@1952:   } keywords[] = {
ds@1952:     { "natural", 7, JT_NATURAL },
ds@1952:     { "left",    4, JT_LEFT|JT_OUTER },
ds@1952:     { "right",   5, JT_RIGHT|JT_OUTER },
ds@1952:     { "full",    4, JT_LEFT|JT_RIGHT|JT_OUTER },
ds@1952:     { "outer",   5, JT_OUTER },
ds@1952:     { "inner",   5, JT_INNER },
ds@1952:     { "cross",   5, JT_INNER|JT_CROSS },
ds@1952:   };
ds@1952:   int i, j;
ds@1952:   apAll[0] = pA;
ds@1952:   apAll[1] = pB;
ds@1952:   apAll[2] = pC;
ds@1952:   for(i=0; i<3 && apAll[i]; i++){
ds@1952:     p = apAll[i];
ds@1952:     for(j=0; j<sizeof(keywords)/sizeof(keywords[0]); j++){
ds@1952:       if( p->n==keywords[j].nChar 
ds@1952:           && sqlite3StrNICmp((char*)p->z, keywords[j].zKeyword, p->n)==0 ){
ds@1952:         jointype |= keywords[j].code;
ds@1952:         break;
ds@1952:       }
ds@1952:     }
ds@1952:     if( j>=sizeof(keywords)/sizeof(keywords[0]) ){
ds@1952:       jointype |= JT_ERROR;
ds@1952:       break;
ds@1952:     }
ds@1952:   }
ds@1952:   if(
ds@1952:      (jointype & (JT_INNER|JT_OUTER))==(JT_INNER|JT_OUTER) ||
ds@1952:      (jointype & JT_ERROR)!=0
ds@1952:   ){
ds@1952:     const char *zSp1 = " ";
ds@1952:     const char *zSp2 = " ";
ds@1952:     if( pB==0 ){ zSp1++; }
ds@1952:     if( pC==0 ){ zSp2++; }
ds@1952:     sqlite3ErrorMsg(pParse, "unknown or unsupported join type: "
ds@1952:        "%T%s%T%s%T", pA, zSp1, pB, zSp2, pC);
ds@1952:     jointype = JT_INNER;
ds@1952:   }else if( jointype & JT_RIGHT ){
ds@1952:     sqlite3ErrorMsg(pParse, 
ds@1952:       "RIGHT and FULL OUTER JOINs are not currently supported");
ds@1952:     jointype = JT_INNER;
ds@1952:   }
ds@1952:   return jointype;
ds@1952: }
ds@1952: 
ds@1952: /*
ds@1952: ** Return the index of a column in a table.  Return -1 if the column
ds@1952: ** is not contained in the table.
ds@1952: */
ds@1952: static int columnIndex(Table *pTab, const char *zCol){
ds@1952:   int i;
ds@1952:   for(i=0; i<pTab->nCol; i++){
ds@1952:     if( sqlite3StrICmp(pTab->aCol[i].zName, zCol)==0 ) return i;
ds@1952:   }
ds@1952:   return -1;
ds@1952: }
ds@1952: 
ds@1952: /*
ds@1952: ** Set the value of a token to a '\000'-terminated string.
ds@1952: */
ds@1952: static void setToken(Token *p, const char *z){
ds@1952:   p->z = (u8*)z;
ds@1952:   p->n = z ? strlen(z) : 0;
ds@1952:   p->dyn = 0;
ds@1952: }
ds@1952: 
ds@1952: /*
ds@1952: ** Set the token to the double-quoted and escaped version of the string pointed
ds@1952: ** to by z. For example;
ds@1952: **
ds@1952: **    {a"bc}  ->  {"a""bc"}
ds@1952: */
ds@1952: static void setQuotedToken(Parse *pParse, Token *p, const char *z){
ds@1952:   p->z = (u8 *)sqlite3MPrintf(0, "\"%w\"", z);
ds@1952:   p->dyn = 1;
ds@1952:   if( p->z ){
ds@1952:     p->n = strlen((char *)p->z);
ds@1952:   }else{
ds@1952:     pParse->db->mallocFailed = 1;
ds@1952:   }
ds@1952: }
ds@1952: 
ds@1952: /*
ds@1952: ** Create an expression node for an identifier with the name of zName
ds@1952: */
ds@1952: Expr *sqlite3CreateIdExpr(Parse *pParse, const char *zName){
ds@1952:   Token dummy;
ds@1952:   setToken(&dummy, zName);
ds@1952:   return sqlite3PExpr(pParse, TK_ID, 0, 0, &dummy);
ds@1952: }
ds@1952: 
ds@1952: 
ds@1952: /*
ds@1952: ** Add a term to the WHERE expression in *ppExpr that requires the
ds@1952: ** zCol column to be equal in the two tables pTab1 and pTab2.
ds@1952: */
ds@1952: static void addWhereTerm(
ds@1952:   Parse *pParse,           /* Parsing context */
ds@1952:   const char *zCol,        /* Name of the column */
ds@1952:   const Table *pTab1,      /* First table */
ds@1952:   const char *zAlias1,     /* Alias for first table.  May be NULL */
ds@1952:   const Table *pTab2,      /* Second table */
ds@1952:   const char *zAlias2,     /* Alias for second table.  May be NULL */
ds@1952:   int iRightJoinTable,     /* VDBE cursor for the right table */
ds@1952:   Expr **ppExpr            /* Add the equality term to this expression */
ds@1952: ){
ds@1952:   Expr *pE1a, *pE1b, *pE1c;
ds@1952:   Expr *pE2a, *pE2b, *pE2c;
ds@1952:   Expr *pE;
ds@1952: 
ds@1952:   pE1a = sqlite3CreateIdExpr(pParse, zCol);
ds@1952:   pE2a = sqlite3CreateIdExpr(pParse, zCol);
ds@1952:   if( zAlias1==0 ){
ds@1952:     zAlias1 = pTab1->zName;
ds@1952:   }
ds@1952:   pE1b = sqlite3CreateIdExpr(pParse, zAlias1);
ds@1952:   if( zAlias2==0 ){
ds@1952:     zAlias2 = pTab2->zName;
ds@1952:   }
ds@1952:   pE2b = sqlite3CreateIdExpr(pParse, zAlias2);
ds@1952:   pE1c = sqlite3PExpr(pParse, TK_DOT, pE1b, pE1a, 0);
ds@1952:   pE2c = sqlite3PExpr(pParse, TK_DOT, pE2b, pE2a, 0);
ds@1952:   pE = sqlite3PExpr(pParse, TK_EQ, pE1c, pE2c, 0);
ds@1952:   if( pE ){
ds@1952:     ExprSetProperty(pE, EP_FromJoin);
ds@1952:     pE->iRightJoinTable = iRightJoinTable;
ds@1952:   }
ds@1952:   pE = sqlite3ExprAnd(pParse->db,*ppExpr, pE);
ds@1952:   if( pE ){
ds@1952:     *ppExpr = pE;
ds@1952:   }
ds@1952: }
ds@1952: 
ds@1952: /*
ds@1952: ** Set the EP_FromJoin property on all terms of the given expression.
ds@1952: ** And set the Expr.iRightJoinTable to iTable for every term in the
ds@1952: ** expression.
ds@1952: **
ds@1952: ** The EP_FromJoin property is used on terms of an expression to tell
ds@1952: ** the LEFT OUTER JOIN processing logic that this term is part of the
ds@1952: ** join restriction specified in the ON or USING clause and not a part
ds@1952: ** of the more general WHERE clause.  These terms are moved over to the
ds@1952: ** WHERE clause during join processing but we need to remember that they
ds@1952: ** originated in the ON or USING clause.
ds@1952: **
ds@1952: ** The Expr.iRightJoinTable tells the WHERE clause processing that the
ds@1952: ** expression depends on table iRightJoinTable even if that table is not
ds@1952: ** explicitly mentioned in the expression.  That information is needed
ds@1952: ** for cases like this:
ds@1952: **
ds@1952: **    SELECT * FROM t1 LEFT JOIN t2 ON t1.a=t2.b AND t1.x=5
ds@1952: **
ds@1952: ** The where clause needs to defer the handling of the t1.x=5
ds@1952: ** term until after the t2 loop of the join.  In that way, a
ds@1952: ** NULL t2 row will be inserted whenever t1.x!=5.  If we do not
ds@1952: ** defer the handling of t1.x=5, it will be processed immediately
ds@1952: ** after the t1 loop and rows with t1.x!=5 will never appear in
ds@1952: ** the output, which is incorrect.
ds@1952: */
ds@1952: static void setJoinExpr(Expr *p, int iTable){
ds@1952:   while( p ){
ds@1952:     ExprSetProperty(p, EP_FromJoin);
ds@1952:     p->iRightJoinTable = iTable;
ds@1952:     setJoinExpr(p->pLeft, iTable);
ds@1952:     p = p->pRight;
ds@1952:   } 
ds@1952: }
ds@1952: 
ds@1952: /*
ds@1952: ** This routine processes the join information for a SELECT statement.
ds@1952: ** ON and USING clauses are converted into extra terms of the WHERE clause.
ds@1952: ** NATURAL joins also create extra WHERE clause terms.
ds@1952: **
ds@1952: ** The terms of a FROM clause are contained in the Select.pSrc structure.
ds@1952: ** The left most table is the first entry in Select.pSrc.  The right-most
ds@1952: ** table is the last entry.  The join operator is held in the entry to
ds@1952: ** the left.  Thus entry 0 contains the join operator for the join between
ds@1952: ** entries 0 and 1.  Any ON or USING clauses associated with the join are
ds@1952: ** also attached to the left entry.
ds@1952: **
ds@1952: ** This routine returns the number of errors encountered.
ds@1952: */
ds@1952: static int sqliteProcessJoin(Parse *pParse, Select *p){
ds@1952:   SrcList *pSrc;                  /* All tables in the FROM clause */
ds@1952:   int i, j;                       /* Loop counters */
ds@1952:   struct SrcList_item *pLeft;     /* Left table being joined */
ds@1952:   struct SrcList_item *pRight;    /* Right table being joined */
ds@1952: 
ds@1952:   pSrc = p->pSrc;
ds@1952:   pLeft = &pSrc->a[0];
ds@1952:   pRight = &pLeft[1];
ds@1952:   for(i=0; i<pSrc->nSrc-1; i++, pRight++, pLeft++){
ds@1952:     Table *pLeftTab = pLeft->pTab;
ds@1952:     Table *pRightTab = pRight->pTab;
ds@1952: 
ds@1952:     if( pLeftTab==0 || pRightTab==0 ) continue;
ds@1952: 
ds@1952:     /* When the NATURAL keyword is present, add WHERE clause terms for
ds@1952:     ** every column that the two tables have in common.
ds@1952:     */
ds@1952:     if( pRight->jointype & JT_NATURAL ){
ds@1952:       if( pRight->pOn || pRight->pUsing ){
ds@1952:         sqlite3ErrorMsg(pParse, "a NATURAL join may not have "
ds@1952:            "an ON or USING clause", 0);
ds@1952:         return 1;
ds@1952:       }
ds@1952:       for(j=0; j<pLeftTab->nCol; j++){
ds@1952:         char *zName = pLeftTab->aCol[j].zName;
ds@1952:         if( columnIndex(pRightTab, zName)>=0 ){
ds@1952:           addWhereTerm(pParse, zName, pLeftTab, pLeft->zAlias, 
ds@1952:                               pRightTab, pRight->zAlias,
ds@1952:                               pRight->iCursor, &p->pWhere);
ds@1952:           
ds@1952:         }
ds@1952:       }
ds@1952:     }
ds@1952: 
ds@1952:     /* Disallow both ON and USING clauses in the same join
ds@1952:     */
ds@1952:     if( pRight->pOn && pRight->pUsing ){
ds@1952:       sqlite3ErrorMsg(pParse, "cannot have both ON and USING "
ds@1952:         "clauses in the same join");
ds@1952:       return 1;
ds@1952:     }
ds@1952: 
ds@1952:     /* Add the ON clause to the end of the WHERE clause, connected by
ds@1952:     ** an AND operator.
ds@1952:     */
ds@1952:     if( pRight->pOn ){
ds@1952:       setJoinExpr(pRight->pOn, pRight->iCursor);
ds@1952:       p->pWhere = sqlite3ExprAnd(pParse->db, p->pWhere, pRight->pOn);
ds@1952:       pRight->pOn = 0;
ds@1952:     }
ds@1952: 
ds@1952:     /* Create extra terms on the WHERE clause for each column named
ds@1952:     ** in the USING clause.  Example: If the two tables to be joined are 
ds@1952:     ** A and B and the USING clause names X, Y, and Z, then add this
ds@1952:     ** to the WHERE clause:    A.X=B.X AND A.Y=B.Y AND A.Z=B.Z
ds@1952:     ** Report an error if any column mentioned in the USING clause is
ds@1952:     ** not contained in both tables to be joined.
ds@1952:     */
ds@1952:     if( pRight->pUsing ){
ds@1952:       IdList *pList = pRight->pUsing;
ds@1952:       for(j=0; j<pList->nId; j++){
ds@1952:         char *zName = pList->a[j].zName;
ds@1952:         if( columnIndex(pLeftTab, zName)<0 || columnIndex(pRightTab, zName)<0 ){
ds@1952:           sqlite3ErrorMsg(pParse, "cannot join using column %s - column "
ds@1952:             "not present in both tables", zName);
ds@1952:           return 1;
ds@1952:         }
ds@1952:         addWhereTerm(pParse, zName, pLeftTab, pLeft->zAlias, 
ds@1952:                             pRightTab, pRight->zAlias,
ds@1952:                             pRight->iCursor, &p->pWhere);
ds@1952:       }
ds@1952:     }
ds@1952:   }
ds@1952:   return 0;
ds@1952: }
ds@1952: 
ds@1952: /*
ds@1952: ** Insert code into "v" that will push the record on the top of the
ds@1952: ** stack into the sorter.
ds@1952: */
ds@1952: static void pushOntoSorter(
ds@1952:   Parse *pParse,         /* Parser context */
ds@1952:   ExprList *pOrderBy,    /* The ORDER BY clause */
ds@1952:   Select *pSelect        /* The whole SELECT statement */
ds@1952: ){
ds@1952:   Vdbe *v = pParse->pVdbe;
ds@1952:   sqlite3ExprCodeExprList(pParse, pOrderBy);
ds@1952:   sqlite3VdbeAddOp(v, OP_Sequence, pOrderBy->iECursor, 0);
ds@1952:   sqlite3VdbeAddOp(v, OP_Pull, pOrderBy->nExpr + 1, 0);
ds@1952:   sqlite3VdbeAddOp(v, OP_MakeRecord, pOrderBy->nExpr + 2, 0);
ds@1952:   sqlite3VdbeAddOp(v, OP_IdxInsert, pOrderBy->iECursor, 0);
ds@1952:   if( pSelect->iLimit>=0 ){
ds@1952:     int addr1, addr2;
ds@1952:     addr1 = sqlite3VdbeAddOp(v, OP_IfMemZero, pSelect->iLimit+1, 0);
ds@1952:     sqlite3VdbeAddOp(v, OP_MemIncr, -1, pSelect->iLimit+1);
ds@1952:     addr2 = sqlite3VdbeAddOp(v, OP_Goto, 0, 0);
ds@1952:     sqlite3VdbeJumpHere(v, addr1);
ds@1952:     sqlite3VdbeAddOp(v, OP_Last, pOrderBy->iECursor, 0);
ds@1952:     sqlite3VdbeAddOp(v, OP_Delete, pOrderBy->iECursor, 0);
ds@1952:     sqlite3VdbeJumpHere(v, addr2);
ds@1952:     pSelect->iLimit = -1;
ds@1952:   }
ds@1952: }
ds@1952: 
ds@1952: /*
ds@1952: ** Add code to implement the OFFSET
ds@1952: */
ds@1952: static void codeOffset(
ds@1952:   Vdbe *v,          /* Generate code into this VM */
ds@1952:   Select *p,        /* The SELECT statement being coded */
ds@1952:   int iContinue,    /* Jump here to skip the current record */
ds@1952:   int nPop          /* Number of times to pop stack when jumping */
ds@1952: ){
ds@1952:   if( p->iOffset>=0 && iContinue!=0 ){
ds@1952:     int addr;
ds@1952:     sqlite3VdbeAddOp(v, OP_MemIncr, -1, p->iOffset);
ds@1952:     addr = sqlite3VdbeAddOp(v, OP_IfMemNeg, p->iOffset, 0);
ds@1952:     if( nPop>0 ){
ds@1952:       sqlite3VdbeAddOp(v, OP_Pop, nPop, 0);
ds@1952:     }
ds@1952:     sqlite3VdbeAddOp(v, OP_Goto, 0, iContinue);
ds@1952:     VdbeComment((v, "# skip OFFSET records"));
ds@1952:     sqlite3VdbeJumpHere(v, addr);
ds@1952:   }
ds@1952: }
ds@1952: 
ds@1952: /*
ds@1952: ** Add code that will check to make sure the top N elements of the
ds@1952: ** stack are distinct.  iTab is a sorting index that holds previously
ds@1952: ** seen combinations of the N values.  A new entry is made in iTab
ds@1952: ** if the current N values are new.
ds@1952: **
ds@1952: ** A jump to addrRepeat is made and the N+1 values are popped from the
ds@1952: ** stack if the top N elements are not distinct.
ds@1952: */
ds@1952: static void codeDistinct(
ds@1952:   Vdbe *v,           /* Generate code into this VM */
ds@1952:   int iTab,          /* A sorting index used to test for distinctness */
ds@1952:   int addrRepeat,    /* Jump to here if not distinct */
ds@1952:   int N              /* The top N elements of the stack must be distinct */
ds@1952: ){
ds@1952:   sqlite3VdbeAddOp(v, OP_MakeRecord, -N, 0);
ds@1952:   sqlite3VdbeAddOp(v, OP_Distinct, iTab, sqlite3VdbeCurrentAddr(v)+3);
ds@1952:   sqlite3VdbeAddOp(v, OP_Pop, N+1, 0);
ds@1952:   sqlite3VdbeAddOp(v, OP_Goto, 0, addrRepeat);
ds@1952:   VdbeComment((v, "# skip indistinct records"));
ds@1952:   sqlite3VdbeAddOp(v, OP_IdxInsert, iTab, 0);
ds@1952: }
ds@1952: 
ds@1952: /*
ds@1952: ** Generate an error message when a SELECT is used within a subexpression
ds@1952: ** (example:  "a IN (SELECT * FROM table)") but it has more than 1 result
ds@1952: ** column.  We do this in a subroutine because the error occurs in multiple
ds@1952: ** places.
ds@1952: */
ds@1952: static int checkForMultiColumnSelectError(Parse *pParse, int eDest, int nExpr){
ds@1952:   if( nExpr>1 && (eDest==SRT_Mem || eDest==SRT_Set) ){
ds@1952:     sqlite3ErrorMsg(pParse, "only a single result allowed for "
ds@1952:        "a SELECT that is part of an expression");
ds@1952:     return 1;
ds@1952:   }else{
ds@1952:     return 0;
ds@1952:   }
ds@1952: }
ds@1952: 
ds@1952: /*
ds@1952: ** This routine generates the code for the inside of the inner loop
ds@1952: ** of a SELECT.
ds@1952: **
ds@1952: ** If srcTab and nColumn are both zero, then the pEList expressions
ds@1952: ** are evaluated in order to get the data for this row.  If nColumn>0
ds@1952: ** then data is pulled from srcTab and pEList is used only to get the
ds@1952: ** datatypes for each column.
ds@1952: */
ds@1952: static int selectInnerLoop(
ds@1952:   Parse *pParse,          /* The parser context */
ds@1952:   Select *p,              /* The complete select statement being coded */
ds@1952:   ExprList *pEList,       /* List of values being extracted */
ds@1952:   int srcTab,             /* Pull data from this table */
ds@1952:   int nColumn,            /* Number of columns in the source table */
ds@1952:   ExprList *pOrderBy,     /* If not NULL, sort results using this key */
ds@1952:   int distinct,           /* If >=0, make sure results are distinct */
ds@1952:   int eDest,              /* How to dispose of the results */
ds@1952:   int iParm,              /* An argument to the disposal method */
ds@1952:   int iContinue,          /* Jump here to continue with next row */
ds@1952:   int iBreak,             /* Jump here to break out of the inner loop */
ds@1952:   char *aff               /* affinity string if eDest is SRT_Union */
ds@1952: ){
ds@1952:   Vdbe *v = pParse->pVdbe;
ds@1952:   int i;
ds@1952:   int hasDistinct;        /* True if the DISTINCT keyword is present */
ds@1952: 
ds@1952:   if( v==0 ) return 0;
ds@1952:   assert( pEList!=0 );
ds@1952: 
ds@1952:   /* If there was a LIMIT clause on the SELECT statement, then do the check
ds@1952:   ** to see if this row should be output.
ds@1952:   */
ds@1952:   hasDistinct = distinct>=0 && pEList->nExpr>0;
ds@1952:   if( pOrderBy==0 && !hasDistinct ){
ds@1952:     codeOffset(v, p, iContinue, 0);
ds@1952:   }
ds@1952: 
ds@1952:   /* Pull the requested columns.
ds@1952:   */
ds@1952:   if( nColumn>0 ){
ds@1952:     for(i=0; i<nColumn; i++){
ds@1952:       sqlite3VdbeAddOp(v, OP_Column, srcTab, i);
ds@1952:     }
ds@1952:   }else{
ds@1952:     nColumn = pEList->nExpr;
ds@1952:     sqlite3ExprCodeExprList(pParse, pEList);
ds@1952:   }
ds@1952: 
ds@1952:   /* If the DISTINCT keyword was present on the SELECT statement
ds@1952:   ** and this row has been seen before, then do not make this row
ds@1952:   ** part of the result.
ds@1952:   */
ds@1952:   if( hasDistinct ){
ds@1952:     assert( pEList!=0 );
ds@1952:     assert( pEList->nExpr==nColumn );
ds@1952:     codeDistinct(v, distinct, iContinue, nColumn);
ds@1952:     if( pOrderBy==0 ){
ds@1952:       codeOffset(v, p, iContinue, nColumn);
ds@1952:     }
ds@1952:   }
ds@1952: 
ds@1952:   if( checkForMultiColumnSelectError(pParse, eDest, pEList->nExpr) ){
ds@1952:     return 0;
ds@1952:   }
ds@1952: 
ds@1952:   switch( eDest ){
ds@1952:     /* In this mode, write each query result to the key of the temporary
ds@1952:     ** table iParm.
ds@1952:     */
ds@1952: #ifndef SQLITE_OMIT_COMPOUND_SELECT
ds@1952:     case SRT_Union: {
ds@1952:       sqlite3VdbeAddOp(v, OP_MakeRecord, nColumn, 0);
ds@1952:       if( aff ){
ds@1952:         sqlite3VdbeChangeP3(v, -1, aff, P3_STATIC);
ds@1952:       }
ds@1952:       sqlite3VdbeAddOp(v, OP_IdxInsert, iParm, 0);
ds@1952:       break;
ds@1952:     }
ds@1952: 
ds@1952:     /* Construct a record from the query result, but instead of
ds@1952:     ** saving that record, use it as a key to delete elements from
ds@1952:     ** the temporary table iParm.
ds@1952:     */
ds@1952:     case SRT_Except: {
ds@1952:       int addr;
ds@1952:       addr = sqlite3VdbeAddOp(v, OP_MakeRecord, nColumn, 0);
ds@1952:       sqlite3VdbeChangeP3(v, -1, aff, P3_STATIC);
ds@1952:       sqlite3VdbeAddOp(v, OP_NotFound, iParm, addr+3);
ds@1952:       sqlite3VdbeAddOp(v, OP_Delete, iParm, 0);
ds@1952:       break;
ds@1952:     }
ds@1952: #endif
ds@1952: 
ds@1952:     /* Store the result as data using a unique key.
ds@1952:     */
ds@1952:     case SRT_Table:
ds@1952:     case SRT_EphemTab: {
ds@1952:       sqlite3VdbeAddOp(v, OP_MakeRecord, nColumn, 0);
ds@1952:       if( pOrderBy ){
ds@1952:         pushOntoSorter(pParse, pOrderBy, p);
ds@1952:       }else{
ds@1952:         sqlite3VdbeAddOp(v, OP_NewRowid, iParm, 0);
ds@1952:         sqlite3VdbeAddOp(v, OP_Pull, 1, 0);
ds@1952:         sqlite3VdbeAddOp(v, OP_Insert, iParm, OPFLAG_APPEND);
ds@1952:       }
ds@1952:       break;
ds@1952:     }
ds@1952: 
ds@1952: #ifndef SQLITE_OMIT_SUBQUERY
ds@1952:     /* If we are creating a set for an "expr IN (SELECT ...)" construct,
ds@1952:     ** then there should be a single item on the stack.  Write this
ds@1952:     ** item into the set table with bogus data.
ds@1952:     */
ds@1952:     case SRT_Set: {
ds@1952:       int addr1 = sqlite3VdbeCurrentAddr(v);
ds@1952:       int addr2;
ds@1952: 
ds@1952:       assert( nColumn==1 );
ds@1952:       sqlite3VdbeAddOp(v, OP_NotNull, -1, addr1+3);
ds@1952:       sqlite3VdbeAddOp(v, OP_Pop, 1, 0);
ds@1952:       addr2 = sqlite3VdbeAddOp(v, OP_Goto, 0, 0);
ds@1952:       p->affinity = sqlite3CompareAffinity(pEList->a[0].pExpr,(iParm>>16)&0xff);
ds@1952:       if( pOrderBy ){
ds@1952:         /* At first glance you would think we could optimize out the
ds@1952:         ** ORDER BY in this case since the order of entries in the set
ds@1952:         ** does not matter.  But there might be a LIMIT clause, in which
ds@1952:         ** case the order does matter */
ds@1952:         pushOntoSorter(pParse, pOrderBy, p);
ds@1952:       }else{
ds@1952:         sqlite3VdbeOp3(v, OP_MakeRecord, 1, 0, &p->affinity, 1);
ds@1952:         sqlite3VdbeAddOp(v, OP_IdxInsert, (iParm&0x0000FFFF), 0);
ds@1952:       }
ds@1952:       sqlite3VdbeJumpHere(v, addr2);
ds@1952:       break;
ds@1952:     }
ds@1952: 
ds@1952:     /* If any row exist in the result set, record that fact and abort.
ds@1952:     */
ds@1952:     case SRT_Exists: {
ds@1952:       sqlite3VdbeAddOp(v, OP_MemInt, 1, iParm);
ds@1952:       sqlite3VdbeAddOp(v, OP_Pop, nColumn, 0);
ds@1952:       /* The LIMIT clause will terminate the loop for us */
ds@1952:       break;
ds@1952:     }
ds@1952: 
ds@1952:     /* If this is a scalar select that is part of an expression, then
ds@1952:     ** store the results in the appropriate memory cell and break out
ds@1952:     ** of the scan loop.
ds@1952:     */
ds@1952:     case SRT_Mem: {
ds@1952:       assert( nColumn==1 );
ds@1952:       if( pOrderBy ){
ds@1952:         pushOntoSorter(pParse, pOrderBy, p);
ds@1952:       }else{
ds@1952:         sqlite3VdbeAddOp(v, OP_MemStore, iParm, 1);
ds@1952:         /* The LIMIT clause will jump out of the loop for us */
ds@1952:       }
ds@1952:       break;
ds@1952:     }
ds@1952: #endif /* #ifndef SQLITE_OMIT_SUBQUERY */
ds@1952: 
ds@1952:     /* Send the data to the callback function or to a subroutine.  In the
ds@1952:     ** case of a subroutine, the subroutine itself is responsible for
ds@1952:     ** popping the data from the stack.
ds@1952:     */
ds@1952:     case SRT_Subroutine:
ds@1952:     case SRT_Callback: {
ds@1952:       if( pOrderBy ){
ds@1952:         sqlite3VdbeAddOp(v, OP_MakeRecord, nColumn, 0);
ds@1952:         pushOntoSorter(pParse, pOrderBy, p);
ds@1952:       }else if( eDest==SRT_Subroutine ){
ds@1952:         sqlite3VdbeAddOp(v, OP_Gosub, 0, iParm);
ds@1952:       }else{
ds@1952:         sqlite3VdbeAddOp(v, OP_Callback, nColumn, 0);
ds@1952:       }
ds@1952:       break;
ds@1952:     }
ds@1952: 
ds@1952: #if !defined(SQLITE_OMIT_TRIGGER)
ds@1952:     /* Discard the results.  This is used for SELECT statements inside
ds@1952:     ** the body of a TRIGGER.  The purpose of such selects is to call
ds@1952:     ** user-defined functions that have side effects.  We do not care
ds@1952:     ** about the actual results of the select.
ds@1952:     */
ds@1952:     default: {
ds@1952:       assert( eDest==SRT_Discard );
ds@1952:       sqlite3VdbeAddOp(v, OP_Pop, nColumn, 0);
ds@1952:       break;
ds@1952:     }
ds@1952: #endif
ds@1952:   }
ds@1952: 
ds@1952:   /* Jump to the end of the loop if the LIMIT is reached.
ds@1952:   */
ds@1952:   if( p->iLimit>=0 && pOrderBy==0 ){
ds@1952:     sqlite3VdbeAddOp(v, OP_MemIncr, -1, p->iLimit);
ds@1952:     sqlite3VdbeAddOp(v, OP_IfMemZero, p->iLimit, iBreak);
ds@1952:   }
ds@1952:   return 0;
ds@1952: }
ds@1952: 
ds@1952: /*
ds@1952: ** Given an expression list, generate a KeyInfo structure that records
ds@1952: ** the collating sequence for each expression in that expression list.
ds@1952: **
ds@1952: ** If the ExprList is an ORDER BY or GROUP BY clause then the resulting
ds@1952: ** KeyInfo structure is appropriate for initializing a virtual index to
ds@1952: ** implement that clause.  If the ExprList is the result set of a SELECT
ds@1952: ** then the KeyInfo structure is appropriate for initializing a virtual
ds@1952: ** index to implement a DISTINCT test.
ds@1952: **
ds@1952: ** Space to hold the KeyInfo structure is obtain from malloc.  The calling
ds@1952: ** function is responsible for seeing that this structure is eventually
ds@1952: ** freed.  Add the KeyInfo structure to the P3 field of an opcode using
ds@1952: ** P3_KEYINFO_HANDOFF is the usual way of dealing with this.
ds@1952: */
ds@1952: static KeyInfo *keyInfoFromExprList(Parse *pParse, ExprList *pList){
ds@1952:   sqlite3 *db = pParse->db;
ds@1952:   int nExpr;
ds@1952:   KeyInfo *pInfo;
ds@1952:   struct ExprList_item *pItem;
ds@1952:   int i;
ds@1952: 
ds@1952:   nExpr = pList->nExpr;
ds@1952:   pInfo = sqlite3DbMallocZero(db, sizeof(*pInfo) + nExpr*(sizeof(CollSeq*)+1) );
ds@1952:   if( pInfo ){
ds@1952:     pInfo->aSortOrder = (u8*)&pInfo->aColl[nExpr];
ds@1952:     pInfo->nField = nExpr;
ds@1952:     pInfo->enc = ENC(db);
ds@1952:     for(i=0, pItem=pList->a; i<nExpr; i++, pItem++){
ds@1952:       CollSeq *pColl;
ds@1952:       pColl = sqlite3ExprCollSeq(pParse, pItem->pExpr);
ds@1952:       if( !pColl ){
ds@1952:         pColl = db->pDfltColl;
ds@1952:       }
ds@1952:       pInfo->aColl[i] = pColl;
ds@1952:       pInfo->aSortOrder[i] = pItem->sortOrder;
ds@1952:     }
ds@1952:   }
ds@1952:   return pInfo;
ds@1952: }
ds@1952: 
ds@1952: 
ds@1952: /*
ds@1952: ** If the inner loop was generated using a non-null pOrderBy argument,
ds@1952: ** then the results were placed in a sorter.  After the loop is terminated
ds@1952: ** we need to run the sorter and output the results.  The following
ds@1952: ** routine generates the code needed to do that.
ds@1952: */
ds@1952: static void generateSortTail(
ds@1952:   Parse *pParse,   /* Parsing context */
ds@1952:   Select *p,       /* The SELECT statement */
ds@1952:   Vdbe *v,         /* Generate code into this VDBE */
ds@1952:   int nColumn,     /* Number of columns of data */
ds@1952:   int eDest,       /* Write the sorted results here */
ds@1952:   int iParm        /* Optional parameter associated with eDest */
ds@1952: ){
ds@1952:   int brk = sqlite3VdbeMakeLabel(v);
ds@1952:   int cont = sqlite3VdbeMakeLabel(v);
ds@1952:   int addr;
ds@1952:   int iTab;
ds@1952:   int pseudoTab = 0;
ds@1952:   ExprList *pOrderBy = p->pOrderBy;
ds@1952: 
ds@1952:   iTab = pOrderBy->iECursor;
ds@1952:   if( eDest==SRT_Callback || eDest==SRT_Subroutine ){
ds@1952:     pseudoTab = pParse->nTab++;
ds@1952:     sqlite3VdbeAddOp(v, OP_OpenPseudo, pseudoTab, 0);
ds@1952:     sqlite3VdbeAddOp(v, OP_SetNumColumns, pseudoTab, nColumn);
ds@1952:   }
ds@1952:   addr = 1 + sqlite3VdbeAddOp(v, OP_Sort, iTab, brk);
ds@1952:   codeOffset(v, p, cont, 0);
ds@1952:   if( eDest==SRT_Callback || eDest==SRT_Subroutine ){
ds@1952:     sqlite3VdbeAddOp(v, OP_Integer, 1, 0);
ds@1952:   }
ds@1952:   sqlite3VdbeAddOp(v, OP_Column, iTab, pOrderBy->nExpr + 1);
ds@1952:   switch( eDest ){
ds@1952:     case SRT_Table:
ds@1952:     case SRT_EphemTab: {
ds@1952:       sqlite3VdbeAddOp(v, OP_NewRowid, iParm, 0);
ds@1952:       sqlite3VdbeAddOp(v, OP_Pull, 1, 0);
ds@1952:       sqlite3VdbeAddOp(v, OP_Insert, iParm, OPFLAG_APPEND);
ds@1952:       break;
ds@1952:     }
ds@1952: #ifndef SQLITE_OMIT_SUBQUERY
ds@1952:     case SRT_Set: {
ds@1952:       assert( nColumn==1 );
ds@1952:       sqlite3VdbeAddOp(v, OP_NotNull, -1, sqlite3VdbeCurrentAddr(v)+3);
ds@1952:       sqlite3VdbeAddOp(v, OP_Pop, 1, 0);
ds@1952:       sqlite3VdbeAddOp(v, OP_Goto, 0, sqlite3VdbeCurrentAddr(v)+3);
ds@1952:       sqlite3VdbeOp3(v, OP_MakeRecord, 1, 0, &p->affinity, 1);
ds@1952:       sqlite3VdbeAddOp(v, OP_IdxInsert, (iParm&0x0000FFFF), 0);
ds@1952:       break;
ds@1952:     }
ds@1952:     case SRT_Mem: {
ds@1952:       assert( nColumn==1 );
ds@1952:       sqlite3VdbeAddOp(v, OP_MemStore, iParm, 1);
ds@1952:       /* The LIMIT clause will terminate the loop for us */
ds@1952:       break;
ds@1952:     }
ds@1952: #endif
ds@1952:     case SRT_Callback:
ds@1952:     case SRT_Subroutine: {
ds@1952:       int i;
ds@1952:       sqlite3VdbeAddOp(v, OP_Insert, pseudoTab, 0);
ds@1952:       for(i=0; i<nColumn; i++){
ds@1952:         sqlite3VdbeAddOp(v, OP_Column, pseudoTab, i);
ds@1952:       }
ds@1952:       if( eDest==SRT_Callback ){
ds@1952:         sqlite3VdbeAddOp(v, OP_Callback, nColumn, 0);
ds@1952:       }else{
ds@1952:         sqlite3VdbeAddOp(v, OP_Gosub, 0, iParm);
ds@1952:       }
ds@1952:       break;
ds@1952:     }
ds@1952:     default: {
ds@1952:       /* Do nothing */
ds@1952:       break;
ds@1952:     }
ds@1952:   }
ds@1952: 
ds@1952:   /* Jump to the end of the loop when the LIMIT is reached
ds@1952:   */
ds@1952:   if( p->iLimit>=0 ){
ds@1952:     sqlite3VdbeAddOp(v, OP_MemIncr, -1, p->iLimit);
ds@1952:     sqlite3VdbeAddOp(v, OP_IfMemZero, p->iLimit, brk);
ds@1952:   }
ds@1952: 
ds@1952:   /* The bottom of the loop
ds@1952:   */
ds@1952:   sqlite3VdbeResolveLabel(v, cont);
ds@1952:   sqlite3VdbeAddOp(v, OP_Next, iTab, addr);
ds@1952:   sqlite3VdbeResolveLabel(v, brk);
ds@1952:   if( eDest==SRT_Callback || eDest==SRT_Subroutine ){
ds@1952:     sqlite3VdbeAddOp(v, OP_Close, pseudoTab, 0);
ds@1952:   }
ds@1952: 
ds@1952: }
ds@1952: 
ds@1952: /*
ds@1952: ** Return a pointer to a string containing the 'declaration type' of the
ds@1952: ** expression pExpr. The string may be treated as static by the caller.
ds@1952: **
ds@1952: ** The declaration type is the exact datatype definition extracted from the
ds@1952: ** original CREATE TABLE statement if the expression is a column. The
ds@1952: ** declaration type for a ROWID field is INTEGER. Exactly when an expression
ds@1952: ** is considered a column can be complex in the presence of subqueries. The
ds@1952: ** result-set expression in all of the following SELECT statements is 
ds@1952: ** considered a column by this function.
ds@1952: **
ds@1952: **   SELECT col FROM tbl;
ds@1952: **   SELECT (SELECT col FROM tbl;
ds@1952: **   SELECT (SELECT col FROM tbl);
ds@1952: **   SELECT abc FROM (SELECT col AS abc FROM tbl);
ds@1952: ** 
ds@1952: ** The declaration type for any expression other than a column is NULL.
ds@1952: */
ds@1952: static const char *columnType(
ds@1952:   NameContext *pNC, 
ds@1952:   Expr *pExpr,
ds@1952:   const char **pzOriginDb,
ds@1952:   const char **pzOriginTab,
ds@1952:   const char **pzOriginCol
ds@1952: ){
ds@1952:   char const *zType = 0;
ds@1952:   char const *zOriginDb = 0;
ds@1952:   char const *zOriginTab = 0;
ds@1952:   char const *zOriginCol = 0;
ds@1952:   int j;
ds@1952:   if( pExpr==0 || pNC->pSrcList==0 ) return 0;
ds@1952: 
ds@1952:   switch( pExpr->op ){
ds@1952:     case TK_AGG_COLUMN:
ds@1952:     case TK_COLUMN: {
ds@1952:       /* The expression is a column. Locate the table the column is being
ds@1952:       ** extracted from in NameContext.pSrcList. This table may be real
ds@1952:       ** database table or a subquery.
ds@1952:       */
ds@1952:       Table *pTab = 0;            /* Table structure column is extracted from */
ds@1952:       Select *pS = 0;             /* Select the column is extracted from */
ds@1952:       int iCol = pExpr->iColumn;  /* Index of column in pTab */
ds@1952:       while( pNC && !pTab ){
ds@1952:         SrcList *pTabList = pNC->pSrcList;
ds@1952:         for(j=0;j<pTabList->nSrc && pTabList->a[j].iCursor!=pExpr->iTable;j++);
ds@1952:         if( j<pTabList->nSrc ){
ds@1952:           pTab = pTabList->a[j].pTab;
ds@1952:           pS = pTabList->a[j].pSelect;
ds@1952:         }else{
ds@1952:           pNC = pNC->pNext;
ds@1952:         }
ds@1952:       }
ds@1952: 
ds@1952:       if( pTab==0 ){
ds@1952:         /* FIX ME:
ds@1952:         ** This can occurs if you have something like "SELECT new.x;" inside
ds@1952:         ** a trigger.  In other words, if you reference the special "new"
ds@1952:         ** table in the result set of a select.  We do not have a good way
ds@1952:         ** to find the actual table type, so call it "TEXT".  This is really
ds@1952:         ** something of a bug, but I do not know how to fix it.
ds@1952:         **
ds@1952:         ** This code does not produce the correct answer - it just prevents
ds@1952:         ** a segfault.  See ticket #1229.
ds@1952:         */
ds@1952:         zType = "TEXT";
ds@1952:         break;
ds@1952:       }
ds@1952: 
ds@1952:       assert( pTab );
ds@1952:       if( pS ){
ds@1952:         /* The "table" is actually a sub-select or a view in the FROM clause
ds@1952:         ** of the SELECT statement. Return the declaration type and origin
ds@1952:         ** data for the result-set column of the sub-select.
ds@1952:         */
ds@1952:         if( iCol>=0 && iCol<pS->pEList->nExpr ){
ds@1952:           /* If iCol is less than zero, then the expression requests the
ds@1952:           ** rowid of the sub-select or view. This expression is legal (see 
ds@1952:           ** test case misc2.2.2) - it always evaluates to NULL.
ds@1952:           */
ds@1952:           NameContext sNC;
ds@1952:           Expr *p = pS->pEList->a[iCol].pExpr;
ds@1952:           sNC.pSrcList = pS->pSrc;
ds@1952:           sNC.pNext = 0;
ds@1952:           sNC.pParse = pNC->pParse;
ds@1952:           zType = columnType(&sNC, p, &zOriginDb, &zOriginTab, &zOriginCol); 
ds@1952:         }
ds@1952:       }else if( pTab->pSchema ){
ds@1952:         /* A real table */
ds@1952:         assert( !pS );
ds@1952:         if( iCol<0 ) iCol = pTab->iPKey;
ds@1952:         assert( iCol==-1 || (iCol>=0 && iCol<pTab->nCol) );
ds@1952:         if( iCol<0 ){
ds@1952:           zType = "INTEGER";
ds@1952:           zOriginCol = "rowid";
ds@1952:         }else{
ds@1952:           zType = pTab->aCol[iCol].zType;
ds@1952:           zOriginCol = pTab->aCol[iCol].zName;
ds@1952:         }
ds@1952:         zOriginTab = pTab->zName;
ds@1952:         if( pNC->pParse ){
ds@1952:           int iDb = sqlite3SchemaToIndex(pNC->pParse->db, pTab->pSchema);
ds@1952:           zOriginDb = pNC->pParse->db->aDb[iDb].zName;
ds@1952:         }
ds@1952:       }
ds@1952:       break;
ds@1952:     }
ds@1952: #ifndef SQLITE_OMIT_SUBQUERY
ds@1952:     case TK_SELECT: {
ds@1952:       /* The expression is a sub-select. Return the declaration type and
ds@1952:       ** origin info for the single column in the result set of the SELECT
ds@1952:       ** statement.
ds@1952:       */
ds@1952:       NameContext sNC;
ds@1952:       Select *pS = pExpr->pSelect;
ds@1952:       Expr *p = pS->pEList->a[0].pExpr;
ds@1952:       sNC.pSrcList = pS->pSrc;
ds@1952:       sNC.pNext = pNC;
ds@1952:       sNC.pParse = pNC->pParse;
ds@1952:       zType = columnType(&sNC, p, &zOriginDb, &zOriginTab, &zOriginCol); 
ds@1952:       break;
ds@1952:     }
ds@1952: #endif
ds@1952:   }
ds@1952:   
ds@1952:   if( pzOriginDb ){
ds@1952:     assert( pzOriginTab && pzOriginCol );
ds@1952:     *pzOriginDb = zOriginDb;
ds@1952:     *pzOriginTab = zOriginTab;
ds@1952:     *pzOriginCol = zOriginCol;
ds@1952:   }
ds@1952:   return zType;
ds@1952: }
ds@1952: 
ds@1952: /*
ds@1952: ** Generate code that will tell the VDBE the declaration types of columns
ds@1952: ** in the result set.
ds@1952: */
ds@1952: static void generateColumnTypes(
ds@1952:   Parse *pParse,      /* Parser context */
ds@1952:   SrcList *pTabList,  /* List of tables */
ds@1952:   ExprList *pEList    /* Expressions defining the result set */
ds@1952: ){
ds@1952:   Vdbe *v = pParse->pVdbe;
ds@1952:   int i;
ds@1952:   NameContext sNC;
ds@1952:   sNC.pSrcList = pTabList;
ds@1952:   sNC.pParse = pParse;
ds@1952:   for(i=0; i<pEList->nExpr; i++){
ds@1952:     Expr *p = pEList->a[i].pExpr;
ds@1952:     const char *zOrigDb = 0;
ds@1952:     const char *zOrigTab = 0;
ds@1952:     const char *zOrigCol = 0;
ds@1952:     const char *zType = columnType(&sNC, p, &zOrigDb, &zOrigTab, &zOrigCol);
ds@1952: 
ds@1952:     /* The vdbe must make it's own copy of the column-type and other 
ds@1952:     ** column specific strings, in case the schema is reset before this
ds@1952:     ** virtual machine is deleted.
ds@1952:     */
ds@1952:     sqlite3VdbeSetColName(v, i, COLNAME_DECLTYPE, zType, P3_TRANSIENT);
ds@1952:     sqlite3VdbeSetColName(v, i, COLNAME_DATABASE, zOrigDb, P3_TRANSIENT);
ds@1952:     sqlite3VdbeSetColName(v, i, COLNAME_TABLE, zOrigTab, P3_TRANSIENT);
ds@1952:     sqlite3VdbeSetColName(v, i, COLNAME_COLUMN, zOrigCol, P3_TRANSIENT);
ds@1952:   }
ds@1952: }
ds@1952: 
ds@1952: /*
ds@1952: ** Generate code that will tell the VDBE the names of columns
ds@1952: ** in the result set.  This information is used to provide the
ds@1952: ** azCol[] values in the callback.
ds@1952: */
ds@1952: static void generateColumnNames(
ds@1952:   Parse *pParse,      /* Parser context */
ds@1952:   SrcList *pTabList,  /* List of tables */
ds@1952:   ExprList *pEList    /* Expressions defining the result set */
ds@1952: ){
ds@1952:   Vdbe *v = pParse->pVdbe;
ds@1952:   int i, j;
ds@1952:   sqlite3 *db = pParse->db;
ds@1952:   int fullNames, shortNames;
ds@1952: 
ds@1952: #ifndef SQLITE_OMIT_EXPLAIN
ds@1952:   /* If this is an EXPLAIN, skip this step */
ds@1952:   if( pParse->explain ){
ds@1952:     return;
ds@1952:   }
ds@1952: #endif
ds@1952: 
ds@1952:   assert( v!=0 );
ds@1952:   if( pParse->colNamesSet || v==0 || db->mallocFailed ) return;
ds@1952:   pParse->colNamesSet = 1;
ds@1952:   fullNames = (db->flags & SQLITE_FullColNames)!=0;
ds@1952:   shortNames = (db->flags & SQLITE_ShortColNames)!=0;
ds@1952:   sqlite3VdbeSetNumCols(v, pEList->nExpr);
ds@1952:   for(i=0; i<pEList->nExpr; i++){
ds@1952:     Expr *p;
ds@1952:     p = pEList->a[i].pExpr;
ds@1952:     if( p==0 ) continue;
ds@1952:     if( pEList->a[i].zName ){
ds@1952:       char *zName = pEList->a[i].zName;
ds@1952:       sqlite3VdbeSetColName(v, i, COLNAME_NAME, zName, strlen(zName));
ds@1952:       continue;
ds@1952:     }
ds@1952:     if( p->op==TK_COLUMN && pTabList ){
ds@1952:       Table *pTab;
ds@1952:       char *zCol;
ds@1952:       int iCol = p->iColumn;
ds@1952:       for(j=0; j<pTabList->nSrc && pTabList->a[j].iCursor!=p->iTable; j++){}
ds@1952:       assert( j<pTabList->nSrc );
ds@1952:       pTab = pTabList->a[j].pTab;
ds@1952:       if( iCol<0 ) iCol = pTab->iPKey;
ds@1952:       assert( iCol==-1 || (iCol>=0 && iCol<pTab->nCol) );
ds@1952:       if( iCol<0 ){
ds@1952:         zCol = "rowid";
ds@1952:       }else{
ds@1952:         zCol = pTab->aCol[iCol].zName;
ds@1952:       }
ds@1952:       if( !shortNames && !fullNames && p->span.z && p->span.z[0] ){
ds@1952:         sqlite3VdbeSetColName(v, i, COLNAME_NAME, (char*)p->span.z, p->span.n);
ds@1952:       }else if( fullNames || (!shortNames && pTabList->nSrc>1) ){
ds@1952:         char *zName = 0;
ds@1952:         char *zTab;
ds@1952:  
ds@1952:         zTab = pTabList->a[j].zAlias;
ds@1952:         if( fullNames || zTab==0 ) zTab = pTab->zName;
ds@1952:         sqlite3SetString(&zName, zTab, ".", zCol, (char*)0);
ds@1952:         sqlite3VdbeSetColName(v, i, COLNAME_NAME, zName, P3_DYNAMIC);
ds@1952:       }else{
ds@1952:         sqlite3VdbeSetColName(v, i, COLNAME_NAME, zCol, strlen(zCol));
ds@1952:       }
ds@1952:     }else if( p->span.z && p->span.z[0] ){
ds@1952:       sqlite3VdbeSetColName(v, i, COLNAME_NAME, (char*)p->span.z, p->span.n);
ds@1952:       /* sqlite3VdbeCompressSpace(v, addr); */
ds@1952:     }else{
ds@1952:       char zName[30];
ds@1952:       assert( p->op!=TK_COLUMN || pTabList==0 );
ds@1952:       sqlite3_snprintf(sizeof(zName), zName, "column%d", i+1);
ds@1952:       sqlite3VdbeSetColName(v, i, COLNAME_NAME, zName, 0);
ds@1952:     }
ds@1952:   }
ds@1952:   generateColumnTypes(pParse, pTabList, pEList);
ds@1952: }
ds@1952: 
ds@1952: #ifndef SQLITE_OMIT_COMPOUND_SELECT
ds@1952: /*
ds@1952: ** Name of the connection operator, used for error messages.
ds@1952: */
ds@1952: static const char *selectOpName(int id){
ds@1952:   char *z;
ds@1952:   switch( id ){
ds@1952:     case TK_ALL:       z = "UNION ALL";   break;
ds@1952:     case TK_INTERSECT: z = "INTERSECT";   break;
ds@1952:     case TK_EXCEPT:    z = "EXCEPT";      break;
ds@1952:     default:           z = "UNION";       break;
ds@1952:   }
ds@1952:   return z;
ds@1952: }
ds@1952: #endif /* SQLITE_OMIT_COMPOUND_SELECT */
ds@1952: 
ds@1952: /*
ds@1952: ** Forward declaration
ds@1952: */
ds@1952: static int prepSelectStmt(Parse*, Select*);
ds@1952: 
ds@1952: /*
ds@1952: ** Given a SELECT statement, generate a Table structure that describes
ds@1952: ** the result set of that SELECT.
ds@1952: */
ds@1952: Table *sqlite3ResultSetOfSelect(Parse *pParse, char *zTabName, Select *pSelect){
ds@1952:   Table *pTab;
ds@1952:   int i, j;
ds@1952:   ExprList *pEList;
ds@1952:   Column *aCol, *pCol;
ds@1952:   sqlite3 *db = pParse->db;
ds@1952: 
ds@1952:   while( pSelect->pPrior ) pSelect = pSelect->pPrior;
ds@1952:   if( prepSelectStmt(pParse, pSelect) ){
ds@1952:     return 0;
ds@1952:   }
ds@1952:   if( sqlite3SelectResolve(pParse, pSelect, 0) ){
ds@1952:     return 0;
ds@1952:   }
ds@1952:   pTab = sqlite3DbMallocZero(db, sizeof(Table) );
ds@1952:   if( pTab==0 ){
ds@1952:     return 0;
ds@1952:   }
ds@1952:   pTab->nRef = 1;
ds@1952:   pTab->zName = zTabName ? sqlite3DbStrDup(db, zTabName) : 0;
ds@1952:   pEList = pSelect->pEList;
ds@1952:   pTab->nCol = pEList->nExpr;
ds@1952:   assert( pTab->nCol>0 );
ds@1952:   pTab->aCol = aCol = sqlite3DbMallocZero(db, sizeof(pTab->aCol[0])*pTab->nCol);
ds@1952:   for(i=0, pCol=aCol; i<pTab->nCol; i++, pCol++){
ds@1952:     Expr *p, *pR;
ds@1952:     char *zType;
ds@1952:     char *zName;
ds@1952:     int nName;
ds@1952:     CollSeq *pColl;
ds@1952:     int cnt;
ds@1952:     NameContext sNC;
ds@1952:     
ds@1952:     /* Get an appropriate name for the column
ds@1952:     */
ds@1952:     p = pEList->a[i].pExpr;
ds@1952:     assert( p->pRight==0 || p->pRight->token.z==0 || p->pRight->token.z[0]!=0 );
ds@1952:     if( (zName = pEList->a[i].zName)!=0 ){
ds@1952:       /* If the column contains an "AS <name>" phrase, use <name> as the name */
ds@1952:       zName = sqlite3DbStrDup(db, zName);
ds@1952:     }else if( p->op==TK_DOT 
ds@1952:               && (pR=p->pRight)!=0 && pR->token.z && pR->token.z[0] ){
ds@1952:       /* For columns of the from A.B use B as the name */
ds@1952:       zName = sqlite3MPrintf(db, "%T", &pR->token);
ds@1952:     }else if( p->span.z && p->span.z[0] ){
ds@1952:       /* Use the original text of the column expression as its name */
ds@1952:       zName = sqlite3MPrintf(db, "%T", &p->span);
ds@1952:     }else{
ds@1952:       /* If all else fails, make up a name */
ds@1952:       zName = sqlite3MPrintf(db, "column%d", i+1);
ds@1952:     }
ds@1952:     if( !zName || db->mallocFailed ){
ds@1952:       db->mallocFailed = 1;
ds@1952:       sqlite3_free(zName);
ds@1952:       sqlite3DeleteTable(pTab);
ds@1952:       return 0;
ds@1952:     }
ds@1952:     sqlite3Dequote(zName);
ds@1952: 
ds@1952:     /* Make sure the column name is unique.  If the name is not unique,
ds@1952:     ** append a integer to the name so that it becomes unique.
ds@1952:     */
ds@1952:     nName = strlen(zName);
ds@1952:     for(j=cnt=0; j<i; j++){
ds@1952:       if( sqlite3StrICmp(aCol[j].zName, zName)==0 ){
ds@1952:         zName[nName] = 0;
ds@1952:         zName = sqlite3MPrintf(db, "%z:%d", zName, ++cnt);
ds@1952:         j = -1;
ds@1952:         if( zName==0 ) break;
ds@1952:       }
ds@1952:     }
ds@1952:     pCol->zName = zName;
ds@1952: 
ds@1952:     /* Get the typename, type affinity, and collating sequence for the
ds@1952:     ** column.
ds@1952:     */
ds@1952:     memset(&sNC, 0, sizeof(sNC));
ds@1952:     sNC.pSrcList = pSelect->pSrc;
ds@1952:     zType = sqlite3DbStrDup(db, columnType(&sNC, p, 0, 0, 0));
ds@1952:     pCol->zType = zType;
ds@1952:     pCol->affinity = sqlite3ExprAffinity(p);
ds@1952:     pColl = sqlite3ExprCollSeq(pParse, p);
ds@1952:     if( pColl ){
ds@1952:       pCol->zColl = sqlite3DbStrDup(db, pColl->zName);
ds@1952:     }
ds@1952:   }
ds@1952:   pTab->iPKey = -1;
ds@1952:   return pTab;
ds@1952: }
ds@1952: 
ds@1952: /*
ds@1952: ** Prepare a SELECT statement for processing by doing the following
ds@1952: ** things:
ds@1952: **
ds@1952: **    (1)  Make sure VDBE cursor numbers have been assigned to every
ds@1952: **         element of the FROM clause.
ds@1952: **
ds@1952: **    (2)  Fill in the pTabList->a[].pTab fields in the SrcList that 
ds@1952: **         defines FROM clause.  When views appear in the FROM clause,
ds@1952: **         fill pTabList->a[].pSelect with a copy of the SELECT statement
ds@1952: **         that implements the view.  A copy is made of the view's SELECT
ds@1952: **         statement so that we can freely modify or delete that statement
ds@1952: **         without worrying about messing up the presistent representation
ds@1952: **         of the view.
ds@1952: **
ds@1952: **    (3)  Add terms to the WHERE clause to accomodate the NATURAL keyword
ds@1952: **         on joins and the ON and USING clause of joins.
ds@1952: **
ds@1952: **    (4)  Scan the list of columns in the result set (pEList) looking
ds@1952: **         for instances of the "*" operator or the TABLE.* operator.
ds@1952: **         If found, expand each "*" to be every column in every table
ds@1952: **         and TABLE.* to be every column in TABLE.
ds@1952: **
ds@1952: ** Return 0 on success.  If there are problems, leave an error message
ds@1952: ** in pParse and return non-zero.
ds@1952: */
ds@1952: static int prepSelectStmt(Parse *pParse, Select *p){
ds@1952:   int i, j, k, rc;
ds@1952:   SrcList *pTabList;
ds@1952:   ExprList *pEList;
ds@1952:   struct SrcList_item *pFrom;
ds@1952:   sqlite3 *db = pParse->db;
ds@1952: 
ds@1952:   if( p==0 || p->pSrc==0 || db->mallocFailed ){
ds@1952:     return 1;
ds@1952:   }
ds@1952:   pTabList = p->pSrc;
ds@1952:   pEList = p->pEList;
ds@1952: 
ds@1952:   /* Make sure cursor numbers have been assigned to all entries in
ds@1952:   ** the FROM clause of the SELECT statement.
ds@1952:   */
ds@1952:   sqlite3SrcListAssignCursors(pParse, p->pSrc);
ds@1952: 
ds@1952:   /* Look up every table named in the FROM clause of the select.  If
ds@1952:   ** an entry of the FROM clause is a subquery instead of a table or view,
ds@1952:   ** then create a transient table structure to describe the subquery.
ds@1952:   */
ds@1952:   for(i=0, pFrom=pTabList->a; i<pTabList->nSrc; i++, pFrom++){
ds@1952:     Table *pTab;
ds@1952:     if( pFrom->pTab!=0 ){
ds@1952:       /* This statement has already been prepared.  There is no need
ds@1952:       ** to go further. */
ds@1952:       assert( i==0 );
ds@1952:       return 0;
ds@1952:     }
ds@1952:     if( pFrom->zName==0 ){
ds@1952: #ifndef SQLITE_OMIT_SUBQUERY
ds@1952:       /* A sub-query in the FROM clause of a SELECT */
ds@1952:       assert( pFrom->pSelect!=0 );
ds@1952:       if( pFrom->zAlias==0 ){
ds@1952:         pFrom->zAlias =
ds@1952:           sqlite3MPrintf(db, "sqlite_subquery_%p_", (void*)pFrom->pSelect);
ds@1952:       }
ds@1952:       assert( pFrom->pTab==0 );
ds@1952:       pFrom->pTab = pTab = 
ds@1952:         sqlite3ResultSetOfSelect(pParse, pFrom->zAlias, pFrom->pSelect);
ds@1952:       if( pTab==0 ){
ds@1952:         return 1;
ds@1952:       }
ds@1952:       /* The isEphem flag indicates that the Table structure has been
ds@1952:       ** dynamically allocated and may be freed at any time.  In other words,
ds@1952:       ** pTab is not pointing to a persistent table structure that defines
ds@1952:       ** part of the schema. */
ds@1952:       pTab->isEphem = 1;
ds@1952: #endif
ds@1952:     }else{
ds@1952:       /* An ordinary table or view name in the FROM clause */
ds@1952:       assert( pFrom->pTab==0 );
ds@1952:       pFrom->pTab = pTab = 
ds@1952:         sqlite3LocateTable(pParse,pFrom->zName,pFrom->zDatabase);
ds@1952:       if( pTab==0 ){
ds@1952:         return 1;
ds@1952:       }
ds@1952:       pTab->nRef++;
ds@1952: #if !defined(SQLITE_OMIT_VIEW) || !defined (SQLITE_OMIT_VIRTUALTABLE)
ds@1952:       if( pTab->pSelect || IsVirtual(pTab) ){
ds@1952:         /* We reach here if the named table is a really a view */
ds@1952:         if( sqlite3ViewGetColumnNames(pParse, pTab) ){
ds@1952:           return 1;
ds@1952:         }
ds@1952:         /* If pFrom->pSelect!=0 it means we are dealing with a
ds@1952:         ** view within a view.  The SELECT structure has already been
ds@1952:         ** copied by the outer view so we can skip the copy step here
ds@1952:         ** in the inner view.
ds@1952:         */
ds@1952:         if( pFrom->pSelect==0 ){
ds@1952:           pFrom->pSelect = sqlite3SelectDup(db, pTab->pSelect);
ds@1952:         }
ds@1952:       }
ds@1952: #endif
ds@1952:     }
ds@1952:   }
ds@1952: 
ds@1952:   /* Process NATURAL keywords, and ON and USING clauses of joins.
ds@1952:   */
ds@1952:   if( sqliteProcessJoin(pParse, p) ) return 1;
ds@1952: 
ds@1952:   /* For every "*" that occurs in the column list, insert the names of
ds@1952:   ** all columns in all tables.  And for every TABLE.* insert the names
ds@1952:   ** of all columns in TABLE.  The parser inserted a special expression
ds@1952:   ** with the TK_ALL operator for each "*" that it found in the column list.
ds@1952:   ** The following code just has to locate the TK_ALL expressions and expand
ds@1952:   ** each one to the list of all columns in all tables.
ds@1952:   **
ds@1952:   ** The first loop just checks to see if there are any "*" operators
ds@1952:   ** that need expanding.
ds@1952:   */
ds@1952:   for(k=0; k<pEList->nExpr; k++){
ds@1952:     Expr *pE = pEList->a[k].pExpr;
ds@1952:     if( pE->op==TK_ALL ) break;
ds@1952:     if( pE->op==TK_DOT && pE->pRight && pE->pRight->op==TK_ALL
ds@1952:          && pE->pLeft && pE->pLeft->op==TK_ID ) break;
ds@1952:   }
ds@1952:   rc = 0;
ds@1952:   if( k<pEList->nExpr ){
ds@1952:     /*
ds@1952:     ** If we get here it means the result set contains one or more "*"
ds@1952:     ** operators that need to be expanded.  Loop through each expression
ds@1952:     ** in the result set and expand them one by one.
ds@1952:     */
ds@1952:     struct ExprList_item *a = pEList->a;
ds@1952:     ExprList *pNew = 0;
ds@1952:     int flags = pParse->db->flags;
ds@1952:     int longNames = (flags & SQLITE_FullColNames)!=0 &&
ds@1952:                       (flags & SQLITE_ShortColNames)==0;
ds@1952: 
ds@1952:     for(k=0; k<pEList->nExpr; k++){
ds@1952:       Expr *pE = a[k].pExpr;
ds@1952:       if( pE->op!=TK_ALL &&
ds@1952:            (pE->op!=TK_DOT || pE->pRight==0 || pE->pRight->op!=TK_ALL) ){
ds@1952:         /* This particular expression does not need to be expanded.
ds@1952:         */
ds@1952:         pNew = sqlite3ExprListAppend(pParse, pNew, a[k].pExpr, 0);
ds@1952:         if( pNew ){
ds@1952:           pNew->a[pNew->nExpr-1].zName = a[k].zName;
ds@1952:         }else{
ds@1952:           rc = 1;
ds@1952:         }
ds@1952:         a[k].pExpr = 0;
ds@1952:         a[k].zName = 0;
ds@1952:       }else{
ds@1952:         /* This expression is a "*" or a "TABLE.*" and needs to be
ds@1952:         ** expanded. */
ds@1952:         int tableSeen = 0;      /* Set to 1 when TABLE matches */
ds@1952:         char *zTName;            /* text of name of TABLE */
ds@1952:         if( pE->op==TK_DOT && pE->pLeft ){
ds@1952:           zTName = sqlite3NameFromToken(db, &pE->pLeft->token);
ds@1952:         }else{
ds@1952:           zTName = 0;
ds@1952:         }
ds@1952:         for(i=0, pFrom=pTabList->a; i<pTabList->nSrc; i++, pFrom++){
ds@1952:           Table *pTab = pFrom->pTab;
ds@1952:           char *zTabName = pFrom->zAlias;
ds@1952:           if( zTabName==0 || zTabName[0]==0 ){ 
ds@1952:             zTabName = pTab->zName;
ds@1952:           }
ds@1952:           if( zTName && (zTabName==0 || zTabName[0]==0 || 
ds@1952:                  sqlite3StrICmp(zTName, zTabName)!=0) ){
ds@1952:             continue;
ds@1952:           }
ds@1952:           tableSeen = 1;
ds@1952:           for(j=0; j<pTab->nCol; j++){
ds@1952:             Expr *pExpr, *pRight;
ds@1952:             char *zName = pTab->aCol[j].zName;
ds@1952: 
ds@1952:             /* If a column is marked as 'hidden' (currently only possible
ds@1952:             ** for virtual tables), do not include it in the expanded
ds@1952:             ** result-set list.
ds@1952:             */
ds@1952:             if( IsHiddenColumn(&pTab->aCol[j]) ){
ds@1952:               assert(IsVirtual(pTab));
ds@1952:               continue;
ds@1952:             }
ds@1952: 
ds@1952:             if( i>0 ){
ds@1952:               struct SrcList_item *pLeft = &pTabList->a[i-1];
ds@1952:               if( (pLeft[1].jointype & JT_NATURAL)!=0 &&
ds@1952:                         columnIndex(pLeft->pTab, zName)>=0 ){
ds@1952:                 /* In a NATURAL join, omit the join columns from the 
ds@1952:                 ** table on the right */
ds@1952:                 continue;
ds@1952:               }
ds@1952:               if( sqlite3IdListIndex(pLeft[1].pUsing, zName)>=0 ){
ds@1952:                 /* In a join with a USING clause, omit columns in the
ds@1952:                 ** using clause from the table on the right. */
ds@1952:                 continue;
ds@1952:               }
ds@1952:             }
ds@1952:             pRight = sqlite3PExpr(pParse, TK_ID, 0, 0, 0);
ds@1952:             if( pRight==0 ) break;
ds@1952:             setQuotedToken(pParse, &pRight->token, zName);
ds@1952:             if( zTabName && (longNames || pTabList->nSrc>1) ){
ds@1952:               Expr *pLeft = sqlite3PExpr(pParse, TK_ID, 0, 0, 0);
ds@1952:               pExpr = sqlite3PExpr(pParse, TK_DOT, pLeft, pRight, 0);
ds@1952:               if( pExpr==0 ) break;
ds@1952:               setQuotedToken(pParse, &pLeft->token, zTabName);
ds@1952:               setToken(&pExpr->span, 
ds@1952:                   sqlite3MPrintf(db, "%s.%s", zTabName, zName));
ds@1952:               pExpr->span.dyn = 1;
ds@1952:               pExpr->token.z = 0;
ds@1952:               pExpr->token.n = 0;
ds@1952:               pExpr->token.dyn = 0;
ds@1952:             }else{
ds@1952:               pExpr = pRight;
ds@1952:               pExpr->span = pExpr->token;
ds@1952:               pExpr->span.dyn = 0;
ds@1952:             }
ds@1952:             if( longNames ){
ds@1952:               pNew = sqlite3ExprListAppend(pParse, pNew, pExpr, &pExpr->span);
ds@1952:             }else{
ds@1952:               pNew = sqlite3ExprListAppend(pParse, pNew, pExpr, &pRight->token);
ds@1952:             }
ds@1952:           }
ds@1952:         }
ds@1952:         if( !tableSeen ){
ds@1952:           if( zTName ){
ds@1952:             sqlite3ErrorMsg(pParse, "no such table: %s", zTName);
ds@1952:           }else{
ds@1952:             sqlite3ErrorMsg(pParse, "no tables specified");
ds@1952:           }
ds@1952:           rc = 1;
ds@1952:         }
ds@1952:         sqlite3_free(zTName);
ds@1952:       }
ds@1952:     }
ds@1952:     sqlite3ExprListDelete(pEList);
ds@1952:     p->pEList = pNew;
ds@1952:   }
ds@1952:   if( p->pEList && p->pEList->nExpr>SQLITE_MAX_COLUMN ){
ds@1952:     sqlite3ErrorMsg(pParse, "too many columns in result set");
ds@1952:     rc = SQLITE_ERROR;
ds@1952:   }
ds@1952:   if( db->mallocFailed ){
ds@1952:     rc = SQLITE_NOMEM;
ds@1952:   }
ds@1952:   return rc;
ds@1952: }
ds@1952: 
ds@1952: #ifndef SQLITE_OMIT_COMPOUND_SELECT
ds@1952: /*
ds@1952: ** This routine associates entries in an ORDER BY expression list with
ds@1952: ** columns in a result.  For each ORDER BY expression, the opcode of
ds@1952: ** the top-level node is changed to TK_COLUMN and the iColumn value of
ds@1952: ** the top-level node is filled in with column number and the iTable
ds@1952: ** value of the top-level node is filled with iTable parameter.
ds@1952: **
ds@1952: ** If there are prior SELECT clauses, they are processed first.  A match
ds@1952: ** in an earlier SELECT takes precedence over a later SELECT.
ds@1952: **
ds@1952: ** Any entry that does not match is flagged as an error.  The number
ds@1952: ** of errors is returned.
ds@1952: */
ds@1952: static int matchOrderbyToColumn(
ds@1952:   Parse *pParse,          /* A place to leave error messages */
ds@1952:   Select *pSelect,        /* Match to result columns of this SELECT */
ds@1952:   ExprList *pOrderBy,     /* The ORDER BY values to match against columns */
ds@1952:   int iTable,             /* Insert this value in iTable */
ds@1952:   int mustComplete        /* If TRUE all ORDER BYs must match */
ds@1952: ){
ds@1952:   int nErr = 0;
ds@1952:   int i, j;
ds@1952:   ExprList *pEList;
ds@1952:   sqlite3 *db = pParse->db;
ds@1952: 
ds@1952:   if( pSelect==0 || pOrderBy==0 ) return 1;
ds@1952:   if( mustComplete ){
ds@1952:     for(i=0; i<pOrderBy->nExpr; i++){ pOrderBy->a[i].done = 0; }
ds@1952:   }
ds@1952:   if( prepSelectStmt(pParse, pSelect) ){
ds@1952:     return 1;
ds@1952:   }
ds@1952:   if( pSelect->pPrior ){
ds@1952:     if( matchOrderbyToColumn(pParse, pSelect->pPrior, pOrderBy, iTable, 0) ){
ds@1952:       return 1;
ds@1952:     }
ds@1952:   }
ds@1952:   pEList = pSelect->pEList;
ds@1952:   for(i=0; i<pOrderBy->nExpr; i++){
ds@1952:     struct ExprList_item *pItem;
ds@1952:     Expr *pE = pOrderBy->a[i].pExpr;
ds@1952:     int iCol = -1;
ds@1952:     char *zLabel;
ds@1952: 
ds@1952:     if( pOrderBy->a[i].done ) continue;
ds@1952:     if( sqlite3ExprIsInteger(pE, &iCol) ){
ds@1952:       if( iCol<=0 || iCol>pEList->nExpr ){
ds@1952:         sqlite3ErrorMsg(pParse,
ds@1952:           "ORDER BY position %d should be between 1 and %d",
ds@1952:           iCol, pEList->nExpr);
ds@1952:         nErr++;
ds@1952:         break;
ds@1952:       }
ds@1952:       if( !mustComplete ) continue;
ds@1952:       iCol--;
ds@1952:     }
ds@1952:     if( iCol<0 && (zLabel = sqlite3NameFromToken(db, &pE->token))!=0 ){
ds@1952:       for(j=0, pItem=pEList->a; j<pEList->nExpr; j++, pItem++){
ds@1952:         char *zName;
ds@1952:         int isMatch;
ds@1952:         if( pItem->zName ){
ds@1952:           zName = sqlite3DbStrDup(db, pItem->zName);
ds@1952:         }else{
ds@1952:           zName = sqlite3NameFromToken(db, &pItem->pExpr->token);
ds@1952:         }
ds@1952:         isMatch = zName && sqlite3StrICmp(zName, zLabel)==0;
ds@1952:         sqlite3_free(zName);
ds@1952:         if( isMatch ){
ds@1952:           iCol = j;
ds@1952:           break;
ds@1952:         }
ds@1952:       }
ds@1952:       sqlite3_free(zLabel);
ds@1952:     }
ds@1952:     if( iCol>=0 ){
ds@1952:       pE->op = TK_COLUMN;
ds@1952:       pE->iColumn = iCol;
ds@1952:       pE->iTable = iTable;
ds@1952:       pE->iAgg = -1;
ds@1952:       pOrderBy->a[i].done = 1;
ds@1952:     }else if( mustComplete ){
ds@1952:       sqlite3ErrorMsg(pParse,
ds@1952:         "ORDER BY term number %d does not match any result column", i+1);
ds@1952:       nErr++;
ds@1952:       break;
ds@1952:     }
ds@1952:   }
ds@1952:   return nErr;  
ds@1952: }
ds@1952: #endif /* #ifndef SQLITE_OMIT_COMPOUND_SELECT */
ds@1952: 
ds@1952: /*
ds@1952: ** Get a VDBE for the given parser context.  Create a new one if necessary.
ds@1952: ** If an error occurs, return NULL and leave a message in pParse.
ds@1952: */
ds@1952: Vdbe *sqlite3GetVdbe(Parse *pParse){
ds@1952:   Vdbe *v = pParse->pVdbe;
ds@1952:   if( v==0 ){
ds@1952:     v = pParse->pVdbe = sqlite3VdbeCreate(pParse->db);
ds@1952:   }
ds@1952:   return v;
ds@1952: }
ds@1952: 
ds@1952: 
ds@1952: /*
ds@1952: ** Compute the iLimit and iOffset fields of the SELECT based on the
ds@1952: ** pLimit and pOffset expressions.  pLimit and pOffset hold the expressions
ds@1952: ** that appear in the original SQL statement after the LIMIT and OFFSET
ds@1952: ** keywords.  Or NULL if those keywords are omitted. iLimit and iOffset 
ds@1952: ** are the integer memory register numbers for counters used to compute 
ds@1952: ** the limit and offset.  If there is no limit and/or offset, then 
ds@1952: ** iLimit and iOffset are negative.
ds@1952: **
ds@1952: ** This routine changes the values of iLimit and iOffset only if
ds@1952: ** a limit or offset is defined by pLimit and pOffset.  iLimit and
ds@1952: ** iOffset should have been preset to appropriate default values
ds@1952: ** (usually but not always -1) prior to calling this routine.
ds@1952: ** Only if pLimit!=0 or pOffset!=0 do the limit registers get
ds@1952: ** redefined.  The UNION ALL operator uses this property to force
ds@1952: ** the reuse of the same limit and offset registers across multiple
ds@1952: ** SELECT statements.
ds@1952: */
ds@1952: static void computeLimitRegisters(Parse *pParse, Select *p, int iBreak){
ds@1952:   Vdbe *v = 0;
ds@1952:   int iLimit = 0;
ds@1952:   int iOffset;
ds@1952:   int addr1, addr2;
ds@1952: 
ds@1952:   /* 
ds@1952:   ** "LIMIT -1" always shows all rows.  There is some
ds@1952:   ** contraversy about what the correct behavior should be.
ds@1952:   ** The current implementation interprets "LIMIT 0" to mean
ds@1952:   ** no rows.
ds@1952:   */
ds@1952:   if( p->pLimit ){
ds@1952:     p->iLimit = iLimit = pParse->nMem;
ds@1952:     pParse->nMem += 2;
ds@1952:     v = sqlite3GetVdbe(pParse);
ds@1952:     if( v==0 ) return;
ds@1952:     sqlite3ExprCode(pParse, p->pLimit);
ds@1952:     sqlite3VdbeAddOp(v, OP_MustBeInt, 0, 0);
ds@1952:     sqlite3VdbeAddOp(v, OP_MemStore, iLimit, 1);
ds@1952:     VdbeComment((v, "# LIMIT counter"));
ds@1952:     sqlite3VdbeAddOp(v, OP_IfMemZero, iLimit, iBreak);
ds@1952:     sqlite3VdbeAddOp(v, OP_MemLoad, iLimit, 0);
ds@1952:   }
ds@1952:   if( p->pOffset ){
ds@1952:     p->iOffset = iOffset = pParse->nMem++;
ds@1952:     v = sqlite3GetVdbe(pParse);
ds@1952:     if( v==0 ) return;
ds@1952:     sqlite3ExprCode(pParse, p->pOffset);
ds@1952:     sqlite3VdbeAddOp(v, OP_MustBeInt, 0, 0);
ds@1952:     sqlite3VdbeAddOp(v, OP_MemStore, iOffset, p->pLimit==0);
ds@1952:     VdbeComment((v, "# OFFSET counter"));
ds@1952:     addr1 = sqlite3VdbeAddOp(v, OP_IfMemPos, iOffset, 0);
ds@1952:     sqlite3VdbeAddOp(v, OP_Pop, 1, 0);
ds@1952:     sqlite3VdbeAddOp(v, OP_Integer, 0, 0);
ds@1952:     sqlite3VdbeJumpHere(v, addr1);
ds@1952:     if( p->pLimit ){
ds@1952:       sqlite3VdbeAddOp(v, OP_Add, 0, 0);
ds@1952:     }
ds@1952:   }
ds@1952:   if( p->pLimit ){
ds@1952:     addr1 = sqlite3VdbeAddOp(v, OP_IfMemPos, iLimit, 0);
ds@1952:     sqlite3VdbeAddOp(v, OP_Pop, 1, 0);
ds@1952:     sqlite3VdbeAddOp(v, OP_MemInt, -1, iLimit+1);
ds@1952:     addr2 = sqlite3VdbeAddOp(v, OP_Goto, 0, 0);
ds@1952:     sqlite3VdbeJumpHere(v, addr1);
ds@1952:     sqlite3VdbeAddOp(v, OP_MemStore, iLimit+1, 1);
ds@1952:     VdbeComment((v, "# LIMIT+OFFSET"));
ds@1952:     sqlite3VdbeJumpHere(v, addr2);
ds@1952:   }
ds@1952: }
ds@1952: 
ds@1952: /*
ds@1952: ** Allocate a virtual index to use for sorting.
ds@1952: */
ds@1952: static void createSortingIndex(Parse *pParse, Select *p, ExprList *pOrderBy){
ds@1952:   if( pOrderBy ){
ds@1952:     int addr;
ds@1952:     assert( pOrderBy->iECursor==0 );
ds@1952:     pOrderBy->iECursor = pParse->nTab++;
ds@1952:     addr = sqlite3VdbeAddOp(pParse->pVdbe, OP_OpenEphemeral,
ds@1952:                             pOrderBy->iECursor, pOrderBy->nExpr+1);
ds@1952:     assert( p->addrOpenEphm[2] == -1 );
ds@1952:     p->addrOpenEphm[2] = addr;
ds@1952:   }
ds@1952: }
ds@1952: 
ds@1952: #ifndef SQLITE_OMIT_COMPOUND_SELECT
ds@1952: /*
ds@1952: ** Return the appropriate collating sequence for the iCol-th column of
ds@1952: ** the result set for the compound-select statement "p".  Return NULL if
ds@1952: ** the column has no default collating sequence.
ds@1952: **
ds@1952: ** The collating sequence for the compound select is taken from the
ds@1952: ** left-most term of the select that has a collating sequence.
ds@1952: */
ds@1952: static CollSeq *multiSelectCollSeq(Parse *pParse, Select *p, int iCol){
ds@1952:   CollSeq *pRet;
ds@1952:   if( p->pPrior ){
ds@1952:     pRet = multiSelectCollSeq(pParse, p->pPrior, iCol);
ds@1952:   }else{
ds@1952:     pRet = 0;
ds@1952:   }
ds@1952:   if( pRet==0 ){
ds@1952:     pRet = sqlite3ExprCollSeq(pParse, p->pEList->a[iCol].pExpr);
ds@1952:   }
ds@1952:   return pRet;
ds@1952: }
ds@1952: #endif /* SQLITE_OMIT_COMPOUND_SELECT */
ds@1952: 
ds@1952: #ifndef SQLITE_OMIT_COMPOUND_SELECT
ds@1952: /*
ds@1952: ** This routine is called to process a query that is really the union
ds@1952: ** or intersection of two or more separate queries.
ds@1952: **
ds@1952: ** "p" points to the right-most of the two queries.  the query on the
ds@1952: ** left is p->pPrior.  The left query could also be a compound query
ds@1952: ** in which case this routine will be called recursively. 
ds@1952: **
ds@1952: ** The results of the total query are to be written into a destination
ds@1952: ** of type eDest with parameter iParm.
ds@1952: **
ds@1952: ** Example 1:  Consider a three-way compound SQL statement.
ds@1952: **
ds@1952: **     SELECT a FROM t1 UNION SELECT b FROM t2 UNION SELECT c FROM t3
ds@1952: **
ds@1952: ** This statement is parsed up as follows:
ds@1952: **
ds@1952: **     SELECT c FROM t3
ds@1952: **      |
ds@1952: **      `----->  SELECT b FROM t2
ds@1952: **                |
ds@1952: **                `------>  SELECT a FROM t1
ds@1952: **
ds@1952: ** The arrows in the diagram above represent the Select.pPrior pointer.
ds@1952: ** So if this routine is called with p equal to the t3 query, then
ds@1952: ** pPrior will be the t2 query.  p->op will be TK_UNION in this case.
ds@1952: **
ds@1952: ** Notice that because of the way SQLite parses compound SELECTs, the
ds@1952: ** individual selects always group from left to right.
ds@1952: */
ds@1952: static int multiSelect(
ds@1952:   Parse *pParse,        /* Parsing context */
ds@1952:   Select *p,            /* The right-most of SELECTs to be coded */
ds@1952:   int eDest,            /* \___  Store query results as specified */
ds@1952:   int iParm,            /* /     by these two parameters.         */
ds@1952:   char *aff             /* If eDest is SRT_Union, the affinity string */
ds@1952: ){
ds@1952:   int rc = SQLITE_OK;   /* Success code from a subroutine */
ds@1952:   Select *pPrior;       /* Another SELECT immediately to our left */
ds@1952:   Vdbe *v;              /* Generate code to this VDBE */
ds@1952:   int nCol;             /* Number of columns in the result set */
ds@1952:   ExprList *pOrderBy;   /* The ORDER BY clause on p */
ds@1952:   int aSetP2[2];        /* Set P2 value of these op to number of columns */
ds@1952:   int nSetP2 = 0;       /* Number of slots in aSetP2[] used */
ds@1952: 
ds@1952:   /* Make sure there is no ORDER BY or LIMIT clause on prior SELECTs.  Only
ds@1952:   ** the last (right-most) SELECT in the series may have an ORDER BY or LIMIT.
ds@1952:   */
ds@1952:   if( p==0 || p->pPrior==0 ){
ds@1952:     rc = 1;
ds@1952:     goto multi_select_end;
ds@1952:   }
ds@1952:   pPrior = p->pPrior;
ds@1952:   assert( pPrior->pRightmost!=pPrior );
ds@1952:   assert( pPrior->pRightmost==p->pRightmost );
ds@1952:   if( pPrior->pOrderBy ){
ds@1952:     sqlite3ErrorMsg(pParse,"ORDER BY clause should come after %s not before",
ds@1952:       selectOpName(p->op));
ds@1952:     rc = 1;
ds@1952:     goto multi_select_end;
ds@1952:   }
ds@1952:   if( pPrior->pLimit ){
ds@1952:     sqlite3ErrorMsg(pParse,"LIMIT clause should come after %s not before",
ds@1952:       selectOpName(p->op));
ds@1952:     rc = 1;
ds@1952:     goto multi_select_end;
ds@1952:   }
ds@1952: 
ds@1952:   /* Make sure we have a valid query engine.  If not, create a new one.
ds@1952:   */
ds@1952:   v = sqlite3GetVdbe(pParse);
ds@1952:   if( v==0 ){
ds@1952:     rc = 1;
ds@1952:     goto multi_select_end;
ds@1952:   }
ds@1952: 
ds@1952:   /* Create the destination temporary table if necessary
ds@1952:   */
ds@1952:   if( eDest==SRT_EphemTab ){
ds@1952:     assert( p->pEList );
ds@1952:     assert( nSetP2<sizeof(aSetP2)/sizeof(aSetP2[0]) );
ds@1952:     aSetP2[nSetP2++] = sqlite3VdbeAddOp(v, OP_OpenEphemeral, iParm, 0);
ds@1952:     eDest = SRT_Table;
ds@1952:   }
ds@1952: 
ds@1952:   /* Generate code for the left and right SELECT statements.
ds@1952:   */
ds@1952:   pOrderBy = p->pOrderBy;
ds@1952:   switch( p->op ){
ds@1952:     case TK_ALL: {
ds@1952:       if( pOrderBy==0 ){
ds@1952:         int addr = 0;
ds@1952:         assert( !pPrior->pLimit );
ds@1952:         pPrior->pLimit = p->pLimit;
ds@1952:         pPrior->pOffset = p->pOffset;
ds@1952:         rc = sqlite3Select(pParse, pPrior, eDest, iParm, 0, 0, 0, aff);
ds@1952:         p->pLimit = 0;
ds@1952:         p->pOffset = 0;
ds@1952:         if( rc ){
ds@1952:           goto multi_select_end;
ds@1952:         }
ds@1952:         p->pPrior = 0;
ds@1952:         p->iLimit = pPrior->iLimit;
ds@1952:         p->iOffset = pPrior->iOffset;
ds@1952:         if( p->iLimit>=0 ){
ds@1952:           addr = sqlite3VdbeAddOp(v, OP_IfMemZero, p->iLimit, 0);
ds@1952:           VdbeComment((v, "# Jump ahead if LIMIT reached"));
ds@1952:         }
ds@1952:         rc = sqlite3Select(pParse, p, eDest, iParm, 0, 0, 0, aff);
ds@1952:         p->pPrior = pPrior;
ds@1952:         if( rc ){
ds@1952:           goto multi_select_end;
ds@1952:         }
ds@1952:         if( addr ){
ds@1952:           sqlite3VdbeJumpHere(v, addr);
ds@1952:         }
ds@1952:         break;
ds@1952:       }
ds@1952:       /* For UNION ALL ... ORDER BY fall through to the next case */
ds@1952:     }
ds@1952:     case TK_EXCEPT:
ds@1952:     case TK_UNION: {
ds@1952:       int unionTab;    /* Cursor number of the temporary table holding result */
ds@1952:       int op = 0;      /* One of the SRT_ operations to apply to self */
ds@1952:       int priorOp;     /* The SRT_ operation to apply to prior selects */
ds@1952:       Expr *pLimit, *pOffset; /* Saved values of p->nLimit and p->nOffset */
ds@1952:       int addr;
ds@1952: 
ds@1952:       priorOp = p->op==TK_ALL ? SRT_Table : SRT_Union;
ds@1952:       if( eDest==priorOp && pOrderBy==0 && !p->pLimit && !p->pOffset ){
ds@1952:         /* We can reuse a temporary table generated by a SELECT to our
ds@1952:         ** right.
ds@1952:         */
ds@1952:         unionTab = iParm;
ds@1952:       }else{
ds@1952:         /* We will need to create our own temporary table to hold the
ds@1952:         ** intermediate results.
ds@1952:         */
ds@1952:         unionTab = pParse->nTab++;
ds@1952:         if( pOrderBy && matchOrderbyToColumn(pParse, p, pOrderBy, unionTab,1) ){
ds@1952:           rc = 1;
ds@1952:           goto multi_select_end;
ds@1952:         }
ds@1952:         addr = sqlite3VdbeAddOp(v, OP_OpenEphemeral, unionTab, 0);
ds@1952:         if( priorOp==SRT_Table ){
ds@1952:           assert( nSetP2<sizeof(aSetP2)/sizeof(aSetP2[0]) );
ds@1952:           aSetP2[nSetP2++] = addr;
ds@1952:         }else{
ds@1952:           assert( p->addrOpenEphm[0] == -1 );
ds@1952:           p->addrOpenEphm[0] = addr;
ds@1952:           p->pRightmost->usesEphm = 1;
ds@1952:         }
ds@1952:         createSortingIndex(pParse, p, pOrderBy);
ds@1952:         assert( p->pEList );
ds@1952:       }
ds@1952: 
ds@1952:       /* Code the SELECT statements to our left
ds@1952:       */
ds@1952:       assert( !pPrior->pOrderBy );
ds@1952:       rc = sqlite3Select(pParse, pPrior, priorOp, unionTab, 0, 0, 0, aff);
ds@1952:       if( rc ){
ds@1952:         goto multi_select_end;
ds@1952:       }
ds@1952: 
ds@1952:       /* Code the current SELECT statement
ds@1952:       */
ds@1952:       switch( p->op ){
ds@1952:          case TK_EXCEPT:  op = SRT_Except;   break;
ds@1952:          case TK_UNION:   op = SRT_Union;    break;
ds@1952:          case TK_ALL:     op = SRT_Table;    break;
ds@1952:       }
ds@1952:       p->pPrior = 0;
ds@1952:       p->pOrderBy = 0;
ds@1952:       p->disallowOrderBy = pOrderBy!=0;
ds@1952:       pLimit = p->pLimit;
ds@1952:       p->pLimit = 0;
ds@1952:       pOffset = p->pOffset;
ds@1952:       p->pOffset = 0;
ds@1952:       rc = sqlite3Select(pParse, p, op, unionTab, 0, 0, 0, aff);
ds@1952:       /* Query flattening in sqlite3Select() might refill p->pOrderBy.
ds@1952:       ** Be sure to delete p->pOrderBy, therefore, to avoid a memory leak. */
ds@1952:       sqlite3ExprListDelete(p->pOrderBy);
ds@1952:       p->pPrior = pPrior;
ds@1952:       p->pOrderBy = pOrderBy;
ds@1952:       sqlite3ExprDelete(p->pLimit);
ds@1952:       p->pLimit = pLimit;
ds@1952:       p->pOffset = pOffset;
ds@1952:       p->iLimit = -1;
ds@1952:       p->iOffset = -1;
ds@1952:       if( rc ){
ds@1952:         goto multi_select_end;
ds@1952:       }
ds@1952: 
ds@1952: 
ds@1952:       /* Convert the data in the temporary table into whatever form
ds@1952:       ** it is that we currently need.
ds@1952:       */      
ds@1952:       if( eDest!=priorOp || unionTab!=iParm ){
ds@1952:         int iCont, iBreak, iStart;
ds@1952:         assert( p->pEList );
ds@1952:         if( eDest==SRT_Callback ){
ds@1952:           Select *pFirst = p;
ds@1952:           while( pFirst->pPrior ) pFirst = pFirst->pPrior;
ds@1952:           generateColumnNames(pParse, 0, pFirst->pEList);
ds@1952:         }
ds@1952:         iBreak = sqlite3VdbeMakeLabel(v);
ds@1952:         iCont = sqlite3VdbeMakeLabel(v);
ds@1952:         computeLimitRegisters(pParse, p, iBreak);
ds@1952:         sqlite3VdbeAddOp(v, OP_Rewind, unionTab, iBreak);
ds@1952:         iStart = sqlite3VdbeCurrentAddr(v);
ds@1952:         rc = selectInnerLoop(pParse, p, p->pEList, unionTab, p->pEList->nExpr,
ds@1952:                              pOrderBy, -1, eDest, iParm, 
ds@1952:                              iCont, iBreak, 0);
ds@1952:         if( rc ){
ds@1952:           rc = 1;
ds@1952:           goto multi_select_end;
ds@1952:         }
ds@1952:         sqlite3VdbeResolveLabel(v, iCont);
ds@1952:         sqlite3VdbeAddOp(v, OP_Next, unionTab, iStart);
ds@1952:         sqlite3VdbeResolveLabel(v, iBreak);
ds@1952:         sqlite3VdbeAddOp(v, OP_Close, unionTab, 0);
ds@1952:       }
ds@1952:       break;
ds@1952:     }
ds@1952:     case TK_INTERSECT: {
ds@1952:       int tab1, tab2;
ds@1952:       int iCont, iBreak, iStart;
ds@1952:       Expr *pLimit, *pOffset;
ds@1952:       int addr;
ds@1952: 
ds@1952:       /* INTERSECT is different from the others since it requires
ds@1952:       ** two temporary tables.  Hence it has its own case.  Begin
ds@1952:       ** by allocating the tables we will need.
ds@1952:       */
ds@1952:       tab1 = pParse->nTab++;
ds@1952:       tab2 = pParse->nTab++;
ds@1952:       if( pOrderBy && matchOrderbyToColumn(pParse,p,pOrderBy,tab1,1) ){
ds@1952:         rc = 1;
ds@1952:         goto multi_select_end;
ds@1952:       }
ds@1952:       createSortingIndex(pParse, p, pOrderBy);
ds@1952: 
ds@1952:       addr = sqlite3VdbeAddOp(v, OP_OpenEphemeral, tab1, 0);
ds@1952:       assert( p->addrOpenEphm[0] == -1 );
ds@1952:       p->addrOpenEphm[0] = addr;
ds@1952:       p->pRightmost->usesEphm = 1;
ds@1952:       assert( p->pEList );
ds@1952: 
ds@1952:       /* Code the SELECTs to our left into temporary table "tab1".
ds@1952:       */
ds@1952:       rc = sqlite3Select(pParse, pPrior, SRT_Union, tab1, 0, 0, 0, aff);
ds@1952:       if( rc ){
ds@1952:         goto multi_select_end;
ds@1952:       }
ds@1952: 
ds@1952:       /* Code the current SELECT into temporary table "tab2"
ds@1952:       */
ds@1952:       addr = sqlite3VdbeAddOp(v, OP_OpenEphemeral, tab2, 0);
ds@1952:       assert( p->addrOpenEphm[1] == -1 );
ds@1952:       p->addrOpenEphm[1] = addr;
ds@1952:       p->pPrior = 0;
ds@1952:       pLimit = p->pLimit;
ds@1952:       p->pLimit = 0;
ds@1952:       pOffset = p->pOffset;
ds@1952:       p->pOffset = 0;
ds@1952:       rc = sqlite3Select(pParse, p, SRT_Union, tab2, 0, 0, 0, aff);
ds@1952:       p->pPrior = pPrior;
ds@1952:       sqlite3ExprDelete(p->pLimit);
ds@1952:       p->pLimit = pLimit;
ds@1952:       p->pOffset = pOffset;
ds@1952:       if( rc ){
ds@1952:         goto multi_select_end;
ds@1952:       }
ds@1952: 
ds@1952:       /* Generate code to take the intersection of the two temporary
ds@1952:       ** tables.
ds@1952:       */
ds@1952:       assert( p->pEList );
ds@1952:       if( eDest==SRT_Callback ){
ds@1952:         Select *pFirst = p;
ds@1952:         while( pFirst->pPrior ) pFirst = pFirst->pPrior;
ds@1952:         generateColumnNames(pParse, 0, pFirst->pEList);
ds@1952:       }
ds@1952:       iBreak = sqlite3VdbeMakeLabel(v);
ds@1952:       iCont = sqlite3VdbeMakeLabel(v);
ds@1952:       computeLimitRegisters(pParse, p, iBreak);
ds@1952:       sqlite3VdbeAddOp(v, OP_Rewind, tab1, iBreak);
ds@1952:       iStart = sqlite3VdbeAddOp(v, OP_RowKey, tab1, 0);
ds@1952:       sqlite3VdbeAddOp(v, OP_NotFound, tab2, iCont);
ds@1952:       rc = selectInnerLoop(pParse, p, p->pEList, tab1, p->pEList->nExpr,
ds@1952:                              pOrderBy, -1, eDest, iParm, 
ds@1952:                              iCont, iBreak, 0);
ds@1952:       if( rc ){
ds@1952:         rc = 1;
ds@1952:         goto multi_select_end;
ds@1952:       }
ds@1952:       sqlite3VdbeResolveLabel(v, iCont);
ds@1952:       sqlite3VdbeAddOp(v, OP_Next, tab1, iStart);
ds@1952:       sqlite3VdbeResolveLabel(v, iBreak);
ds@1952:       sqlite3VdbeAddOp(v, OP_Close, tab2, 0);
ds@1952:       sqlite3VdbeAddOp(v, OP_Close, tab1, 0);
ds@1952:       break;
ds@1952:     }
ds@1952:   }
ds@1952: 
ds@1952:   /* Make sure all SELECTs in the statement have the same number of elements
ds@1952:   ** in their result sets.
ds@1952:   */
ds@1952:   assert( p->pEList && pPrior->pEList );
ds@1952:   if( p->pEList->nExpr!=pPrior->pEList->nExpr ){
ds@1952:     sqlite3ErrorMsg(pParse, "SELECTs to the left and right of %s"
ds@1952:       " do not have the same number of result columns", selectOpName(p->op));
ds@1952:     rc = 1;
ds@1952:     goto multi_select_end;
ds@1952:   }
ds@1952: 
ds@1952:   /* Set the number of columns in temporary tables
ds@1952:   */
ds@1952:   nCol = p->pEList->nExpr;
ds@1952:   while( nSetP2 ){
ds@1952:     sqlite3VdbeChangeP2(v, aSetP2[--nSetP2], nCol);
ds@1952:   }
ds@1952: 
ds@1952:   /* Compute collating sequences used by either the ORDER BY clause or
ds@1952:   ** by any temporary tables needed to implement the compound select.
ds@1952:   ** Attach the KeyInfo structure to all temporary tables.  Invoke the
ds@1952:   ** ORDER BY processing if there is an ORDER BY clause.
ds@1952:   **
ds@1952:   ** This section is run by the right-most SELECT statement only.
ds@1952:   ** SELECT statements to the left always skip this part.  The right-most
ds@1952:   ** SELECT might also skip this part if it has no ORDER BY clause and
ds@1952:   ** no temp tables are required.
ds@1952:   */
ds@1952:   if( pOrderBy || p->usesEphm ){
ds@1952:     int i;                        /* Loop counter */
ds@1952:     KeyInfo *pKeyInfo;            /* Collating sequence for the result set */
ds@1952:     Select *pLoop;                /* For looping through SELECT statements */
ds@1952:     int nKeyCol;                  /* Number of entries in pKeyInfo->aCol[] */
ds@1952:     CollSeq **apColl;             /* For looping through pKeyInfo->aColl[] */
ds@1952:     CollSeq **aCopy;              /* A copy of pKeyInfo->aColl[] */
ds@1952: 
ds@1952:     assert( p->pRightmost==p );
ds@1952:     nKeyCol = nCol + (pOrderBy ? pOrderBy->nExpr : 0);
ds@1952:     pKeyInfo = sqlite3DbMallocZero(pParse->db,
ds@1952:                        sizeof(*pKeyInfo)+nKeyCol*(sizeof(CollSeq*) + 1));
ds@1952:     if( !pKeyInfo ){
ds@1952:       rc = SQLITE_NOMEM;
ds@1952:       goto multi_select_end;
ds@1952:     }
ds@1952: 
ds@1952:     pKeyInfo->enc = ENC(pParse->db);
ds@1952:     pKeyInfo->nField = nCol;
ds@1952: 
ds@1952:     for(i=0, apColl=pKeyInfo->aColl; i<nCol; i++, apColl++){
ds@1952:       *apColl = multiSelectCollSeq(pParse, p, i);
ds@1952:       if( 0==*apColl ){
ds@1952:         *apColl = pParse->db->pDfltColl;
ds@1952:       }
ds@1952:     }
ds@1952: 
ds@1952:     for(pLoop=p; pLoop; pLoop=pLoop->pPrior){
ds@1952:       for(i=0; i<2; i++){
ds@1952:         int addr = pLoop->addrOpenEphm[i];
ds@1952:         if( addr<0 ){
ds@1952:           /* If [0] is unused then [1] is also unused.  So we can
ds@1952:           ** always safely abort as soon as the first unused slot is found */
ds@1952:           assert( pLoop->addrOpenEphm[1]<0 );
ds@1952:           break;
ds@1952:         }
ds@1952:         sqlite3VdbeChangeP2(v, addr, nCol);
ds@1952:         sqlite3VdbeChangeP3(v, addr, (char*)pKeyInfo, P3_KEYINFO);
ds@1952:         pLoop->addrOpenEphm[i] = -1;
ds@1952:       }
ds@1952:     }
ds@1952: 
ds@1952:     if( pOrderBy ){
ds@1952:       struct ExprList_item *pOTerm = pOrderBy->a;
ds@1952:       int nOrderByExpr = pOrderBy->nExpr;
ds@1952:       int addr;
ds@1952:       u8 *pSortOrder;
ds@1952: 
ds@1952:       /* Reuse the same pKeyInfo for the ORDER BY as was used above for
ds@1952:       ** the compound select statements.  Except we have to change out the
ds@1952:       ** pKeyInfo->aColl[] values.  Some of the aColl[] values will be
ds@1952:       ** reused when constructing the pKeyInfo for the ORDER BY, so make
ds@1952:       ** a copy.  Sufficient space to hold both the nCol entries for
ds@1952:       ** the compound select and the nOrderbyExpr entries for the ORDER BY
ds@1952:       ** was allocated above.  But we need to move the compound select
ds@1952:       ** entries out of the way before constructing the ORDER BY entries.
ds@1952:       ** Move the compound select entries into aCopy[] where they can be
ds@1952:       ** accessed and reused when constructing the ORDER BY entries.
ds@1952:       ** Because nCol might be greater than or less than nOrderByExpr
ds@1952:       ** we have to use memmove() when doing the copy.
ds@1952:       */
ds@1952:       aCopy = &pKeyInfo->aColl[nOrderByExpr];
ds@1952:       pSortOrder = pKeyInfo->aSortOrder = (u8*)&aCopy[nCol];
ds@1952:       memmove(aCopy, pKeyInfo->aColl, nCol*sizeof(CollSeq*));
ds@1952: 
ds@1952:       apColl = pKeyInfo->aColl;
ds@1952:       for(i=0; i<nOrderByExpr; i++, pOTerm++, apColl++, pSortOrder++){
ds@1952:         Expr *pExpr = pOTerm->pExpr;
ds@1952:         if( (pExpr->flags & EP_ExpCollate) ){
ds@1952:           assert( pExpr->pColl!=0 );
ds@1952:           *apColl = pExpr->pColl;
ds@1952:         }else{
ds@1952:           *apColl = aCopy[pExpr->iColumn];
ds@1952:         }
ds@1952:         *pSortOrder = pOTerm->sortOrder;
ds@1952:       }
ds@1952:       assert( p->pRightmost==p );
ds@1952:       assert( p->addrOpenEphm[2]>=0 );
ds@1952:       addr = p->addrOpenEphm[2];
ds@1952:       sqlite3VdbeChangeP2(v, addr, p->pOrderBy->nExpr+2);
ds@1952:       pKeyInfo->nField = nOrderByExpr;
ds@1952:       sqlite3VdbeChangeP3(v, addr, (char*)pKeyInfo, P3_KEYINFO_HANDOFF);
ds@1952:       pKeyInfo = 0;
ds@1952:       generateSortTail(pParse, p, v, p->pEList->nExpr, eDest, iParm);
ds@1952:     }
ds@1952: 
ds@1952:     sqlite3_free(pKeyInfo);
ds@1952:   }
ds@1952: 
ds@1952: multi_select_end:
ds@1952:   return rc;
ds@1952: }
ds@1952: #endif /* SQLITE_OMIT_COMPOUND_SELECT */
ds@1952: 
ds@1952: #ifndef SQLITE_OMIT_VIEW
ds@1952: /* Forward Declarations */
ds@1952: static void substExprList(sqlite3*, ExprList*, int, ExprList*);
ds@1952: static void substSelect(sqlite3*, Select *, int, ExprList *);
ds@1952: 
ds@1952: /*
ds@1952: ** Scan through the expression pExpr.  Replace every reference to
ds@1952: ** a column in table number iTable with a copy of the iColumn-th
ds@1952: ** entry in pEList.  (But leave references to the ROWID column 
ds@1952: ** unchanged.)
ds@1952: **
ds@1952: ** This routine is part of the flattening procedure.  A subquery
ds@1952: ** whose result set is defined by pEList appears as entry in the
ds@1952: ** FROM clause of a SELECT such that the VDBE cursor assigned to that
ds@1952: ** FORM clause entry is iTable.  This routine make the necessary 
ds@1952: ** changes to pExpr so that it refers directly to the source table
ds@1952: ** of the subquery rather the result set of the subquery.
ds@1952: */
ds@1952: static void substExpr(
ds@1952:   sqlite3 *db,        /* Report malloc errors to this connection */
ds@1952:   Expr *pExpr,        /* Expr in which substitution occurs */
ds@1952:   int iTable,         /* Table to be substituted */
ds@1952:   ExprList *pEList    /* Substitute expressions */
ds@1952: ){
ds@1952:   if( pExpr==0 ) return;
ds@1952:   if( pExpr->op==TK_COLUMN && pExpr->iTable==iTable ){
ds@1952:     if( pExpr->iColumn<0 ){
ds@1952:       pExpr->op = TK_NULL;
ds@1952:     }else{
ds@1952:       Expr *pNew;
ds@1952:       assert( pEList!=0 && pExpr->iColumn<pEList->nExpr );
ds@1952:       assert( pExpr->pLeft==0 && pExpr->pRight==0 && pExpr->pList==0 );
ds@1952:       pNew = pEList->a[pExpr->iColumn].pExpr;
ds@1952:       assert( pNew!=0 );
ds@1952:       pExpr->op = pNew->op;
ds@1952:       assert( pExpr->pLeft==0 );
ds@1952:       pExpr->pLeft = sqlite3ExprDup(db, pNew->pLeft);
ds@1952:       assert( pExpr->pRight==0 );
ds@1952:       pExpr->pRight = sqlite3ExprDup(db, pNew->pRight);
ds@1952:       assert( pExpr->pList==0 );
ds@1952:       pExpr->pList = sqlite3ExprListDup(db, pNew->pList);
ds@1952:       pExpr->iTable = pNew->iTable;
ds@1952:       pExpr->pTab = pNew->pTab;
ds@1952:       pExpr->iColumn = pNew->iColumn;
ds@1952:       pExpr->iAgg = pNew->iAgg;
ds@1952:       sqlite3TokenCopy(db, &pExpr->token, &pNew->token);
ds@1952:       sqlite3TokenCopy(db, &pExpr->span, &pNew->span);
ds@1952:       pExpr->pSelect = sqlite3SelectDup(db, pNew->pSelect);
ds@1952:       pExpr->flags = pNew->flags;
ds@1952:     }
ds@1952:   }else{
ds@1952:     substExpr(db, pExpr->pLeft, iTable, pEList);
ds@1952:     substExpr(db, pExpr->pRight, iTable, pEList);
ds@1952:     substSelect(db, pExpr->pSelect, iTable, pEList);
ds@1952:     substExprList(db, pExpr->pList, iTable, pEList);
ds@1952:   }
ds@1952: }
ds@1952: static void substExprList(
ds@1952:   sqlite3 *db,         /* Report malloc errors here */
ds@1952:   ExprList *pList,     /* List to scan and in which to make substitutes */
ds@1952:   int iTable,          /* Table to be substituted */
ds@1952:   ExprList *pEList     /* Substitute values */
ds@1952: ){
ds@1952:   int i;
ds@1952:   if( pList==0 ) return;
ds@1952:   for(i=0; i<pList->nExpr; i++){
ds@1952:     substExpr(db, pList->a[i].pExpr, iTable, pEList);
ds@1952:   }
ds@1952: }
ds@1952: static void substSelect(
ds@1952:   sqlite3 *db,         /* Report malloc errors here */
ds@1952:   Select *p,           /* SELECT statement in which to make substitutions */
ds@1952:   int iTable,          /* Table to be replaced */
ds@1952:   ExprList *pEList     /* Substitute values */
ds@1952: ){
ds@1952:   if( !p ) return;
ds@1952:   substExprList(db, p->pEList, iTable, pEList);
ds@1952:   substExprList(db, p->pGroupBy, iTable, pEList);
ds@1952:   substExprList(db, p->pOrderBy, iTable, pEList);
ds@1952:   substExpr(db, p->pHaving, iTable, pEList);
ds@1952:   substExpr(db, p->pWhere, iTable, pEList);
ds@1952:   substSelect(db, p->pPrior, iTable, pEList);
ds@1952: }
ds@1952: #endif /* !defined(SQLITE_OMIT_VIEW) */
ds@1952: 
ds@1952: #ifndef SQLITE_OMIT_VIEW
ds@1952: /*
ds@1952: ** This routine attempts to flatten subqueries in order to speed
ds@1952: ** execution.  It returns 1 if it makes changes and 0 if no flattening
ds@1952: ** occurs.
ds@1952: **
ds@1952: ** To understand the concept of flattening, consider the following
ds@1952: ** query:
ds@1952: **
ds@1952: **     SELECT a FROM (SELECT x+y AS a FROM t1 WHERE z<100) WHERE a>5
ds@1952: **
ds@1952: ** The default way of implementing this query is to execute the
ds@1952: ** subquery first and store the results in a temporary table, then
ds@1952: ** run the outer query on that temporary table.  This requires two
ds@1952: ** passes over the data.  Furthermore, because the temporary table
ds@1952: ** has no indices, the WHERE clause on the outer query cannot be
ds@1952: ** optimized.
ds@1952: **
ds@1952: ** This routine attempts to rewrite queries such as the above into
ds@1952: ** a single flat select, like this:
ds@1952: **
ds@1952: **     SELECT x+y AS a FROM t1 WHERE z<100 AND a>5
ds@1952: **
ds@1952: ** The code generated for this simpification gives the same result
ds@1952: ** but only has to scan the data once.  And because indices might 
ds@1952: ** exist on the table t1, a complete scan of the data might be
ds@1952: ** avoided.
ds@1952: **
ds@1952: ** Flattening is only attempted if all of the following are true:
ds@1952: **
ds@1952: **   (1)  The subquery and the outer query do not both use aggregates.
ds@1952: **
ds@1952: **   (2)  The subquery is not an aggregate or the outer query is not a join.
ds@1952: **
ds@1952: **   (3)  The subquery is not the right operand of a left outer join, or
ds@1952: **        the subquery is not itself a join.  (Ticket #306)
ds@1952: **
ds@1952: **   (4)  The subquery is not DISTINCT or the outer query is not a join.
ds@1952: **
ds@1952: **   (5)  The subquery is not DISTINCT or the outer query does not use
ds@1952: **        aggregates.
ds@1952: **
ds@1952: **   (6)  The subquery does not use aggregates or the outer query is not
ds@1952: **        DISTINCT.
ds@1952: **
ds@1952: **   (7)  The subquery has a FROM clause.
ds@1952: **
ds@1952: **   (8)  The subquery does not use LIMIT or the outer query is not a join.
ds@1952: **
ds@1952: **   (9)  The subquery does not use LIMIT or the outer query does not use
ds@1952: **        aggregates.
ds@1952: **
ds@1952: **  (10)  The subquery does not use aggregates or the outer query does not
ds@1952: **        use LIMIT.
ds@1952: **
ds@1952: **  (11)  The subquery and the outer query do not both have ORDER BY clauses.
ds@1952: **
ds@1952: **  (12)  The subquery is not the right term of a LEFT OUTER JOIN or the
ds@1952: **        subquery has no WHERE clause.  (added by ticket #350)
ds@1952: **
ds@1952: **  (13)  The subquery and outer query do not both use LIMIT
ds@1952: **
ds@1952: **  (14)  The subquery does not use OFFSET
ds@1952: **
ds@1952: **  (15)  The outer query is not part of a compound select or the
ds@1952: **        subquery does not have both an ORDER BY and a LIMIT clause.
ds@1952: **        (See ticket #2339)
ds@1952: **
ds@1952: ** In this routine, the "p" parameter is a pointer to the outer query.
ds@1952: ** The subquery is p->pSrc->a[iFrom].  isAgg is true if the outer query
ds@1952: ** uses aggregates and subqueryIsAgg is true if the subquery uses aggregates.
ds@1952: **
ds@1952: ** If flattening is not attempted, this routine is a no-op and returns 0.
ds@1952: ** If flattening is attempted this routine returns 1.
ds@1952: **
ds@1952: ** All of the expression analysis must occur on both the outer query and
ds@1952: ** the subquery before this routine runs.
ds@1952: */
ds@1952: static int flattenSubquery(
ds@1952:   sqlite3 *db,         /* Database connection */
ds@1952:   Select *p,           /* The parent or outer SELECT statement */
ds@1952:   int iFrom,           /* Index in p->pSrc->a[] of the inner subquery */
ds@1952:   int isAgg,           /* True if outer SELECT uses aggregate functions */
ds@1952:   int subqueryIsAgg    /* True if the subquery uses aggregate functions */
ds@1952: ){
ds@1952:   Select *pSub;       /* The inner query or "subquery" */
ds@1952:   SrcList *pSrc;      /* The FROM clause of the outer query */
ds@1952:   SrcList *pSubSrc;   /* The FROM clause of the subquery */
ds@1952:   ExprList *pList;    /* The result set of the outer query */
ds@1952:   int iParent;        /* VDBE cursor number of the pSub result set temp table */
ds@1952:   int i;              /* Loop counter */
ds@1952:   Expr *pWhere;                    /* The WHERE clause */
ds@1952:   struct SrcList_item *pSubitem;   /* The subquery */
ds@1952: 
ds@1952:   /* Check to see if flattening is permitted.  Return 0 if not.
ds@1952:   */
ds@1952:   if( p==0 ) return 0;
ds@1952:   pSrc = p->pSrc;
ds@1952:   assert( pSrc && iFrom>=0 && iFrom<pSrc->nSrc );
ds@1952:   pSubitem = &pSrc->a[iFrom];
ds@1952:   pSub = pSubitem->pSelect;
ds@1952:   assert( pSub!=0 );
ds@1952:   if( isAgg && subqueryIsAgg ) return 0;                 /* Restriction (1)  */
ds@1952:   if( subqueryIsAgg && pSrc->nSrc>1 ) return 0;          /* Restriction (2)  */
ds@1952:   pSubSrc = pSub->pSrc;
ds@1952:   assert( pSubSrc );
ds@1952:   /* Prior to version 3.1.2, when LIMIT and OFFSET had to be simple constants,
ds@1952:   ** not arbitrary expresssions, we allowed some combining of LIMIT and OFFSET
ds@1952:   ** because they could be computed at compile-time.  But when LIMIT and OFFSET
ds@1952:   ** became arbitrary expressions, we were forced to add restrictions (13)
ds@1952:   ** and (14). */
ds@1952:   if( pSub->pLimit && p->pLimit ) return 0;              /* Restriction (13) */
ds@1952:   if( pSub->pOffset ) return 0;                          /* Restriction (14) */
ds@1952:   if( p->pRightmost && pSub->pLimit && pSub->pOrderBy ){
ds@1952:     return 0;                                            /* Restriction (15) */
ds@1952:   }
ds@1952:   if( pSubSrc->nSrc==0 ) return 0;                       /* Restriction (7)  */
ds@1952:   if( (pSub->isDistinct || pSub->pLimit) 
ds@1952:          && (pSrc->nSrc>1 || isAgg) ){          /* Restrictions (4)(5)(8)(9) */
ds@1952:      return 0;       
ds@1952:   }
ds@1952:   if( p->isDistinct && subqueryIsAgg ) return 0;         /* Restriction (6)  */
ds@1952:   if( (p->disallowOrderBy || p->pOrderBy) && pSub->pOrderBy ){
ds@1952:      return 0;                                           /* Restriction (11) */
ds@1952:   }
ds@1952: 
ds@1952:   /* Restriction 3:  If the subquery is a join, make sure the subquery is 
ds@1952:   ** not used as the right operand of an outer join.  Examples of why this
ds@1952:   ** is not allowed:
ds@1952:   **
ds@1952:   **         t1 LEFT OUTER JOIN (t2 JOIN t3)
ds@1952:   **
ds@1952:   ** If we flatten the above, we would get
ds@1952:   **
ds@1952:   **         (t1 LEFT OUTER JOIN t2) JOIN t3
ds@1952:   **
ds@1952:   ** which is not at all the same thing.
ds@1952:   */
ds@1952:   if( pSubSrc->nSrc>1 && (pSubitem->jointype & JT_OUTER)!=0 ){
ds@1952:     return 0;
ds@1952:   }
ds@1952: 
ds@1952:   /* Restriction 12:  If the subquery is the right operand of a left outer
ds@1952:   ** join, make sure the subquery has no WHERE clause.
ds@1952:   ** An examples of why this is not allowed:
ds@1952:   **
ds@1952:   **         t1 LEFT OUTER JOIN (SELECT * FROM t2 WHERE t2.x>0)
ds@1952:   **
ds@1952:   ** If we flatten the above, we would get
ds@1952:   **
ds@1952:   **         (t1 LEFT OUTER JOIN t2) WHERE t2.x>0
ds@1952:   **
ds@1952:   ** But the t2.x>0 test will always fail on a NULL row of t2, which
ds@1952:   ** effectively converts the OUTER JOIN into an INNER JOIN.
ds@1952:   */
ds@1952:   if( (pSubitem->jointype & JT_OUTER)!=0 && pSub->pWhere!=0 ){
ds@1952:     return 0;
ds@1952:   }
ds@1952: 
ds@1952:   /* If we reach this point, it means flattening is permitted for the
ds@1952:   ** iFrom-th entry of the FROM clause in the outer query.
ds@1952:   */
ds@1952: 
ds@1952:   /* Move all of the FROM elements of the subquery into the
ds@1952:   ** the FROM clause of the outer query.  Before doing this, remember
ds@1952:   ** the cursor number for the original outer query FROM element in
ds@1952:   ** iParent.  The iParent cursor will never be used.  Subsequent code
ds@1952:   ** will scan expressions looking for iParent references and replace
ds@1952:   ** those references with expressions that resolve to the subquery FROM
ds@1952:   ** elements we are now copying in.
ds@1952:   */
ds@1952:   iParent = pSubitem->iCursor;
ds@1952:   {
ds@1952:     int nSubSrc = pSubSrc->nSrc;
ds@1952:     int jointype = pSubitem->jointype;
ds@1952: 
ds@1952:     sqlite3DeleteTable(pSubitem->pTab);
ds@1952:     sqlite3_free(pSubitem->zDatabase);
ds@1952:     sqlite3_free(pSubitem->zName);
ds@1952:     sqlite3_free(pSubitem->zAlias);
ds@1952:     if( nSubSrc>1 ){
ds@1952:       int extra = nSubSrc - 1;
ds@1952:       for(i=1; i<nSubSrc; i++){
ds@1952:         pSrc = sqlite3SrcListAppend(db, pSrc, 0, 0);
ds@1952:       }
ds@1952:       p->pSrc = pSrc;
ds@1952:       for(i=pSrc->nSrc-1; i-extra>=iFrom; i--){
ds@1952:         pSrc->a[i] = pSrc->a[i-extra];
ds@1952:       }
ds@1952:     }
ds@1952:     for(i=0; i<nSubSrc; i++){
ds@1952:       pSrc->a[i+iFrom] = pSubSrc->a[i];
ds@1952:       memset(&pSubSrc->a[i], 0, sizeof(pSubSrc->a[i]));
ds@1952:     }
ds@1952:     pSrc->a[iFrom].jointype = jointype;
ds@1952:   }
ds@1952: 
ds@1952:   /* Now begin substituting subquery result set expressions for 
ds@1952:   ** references to the iParent in the outer query.
ds@1952:   ** 
ds@1952:   ** Example:
ds@1952:   **
ds@1952:   **   SELECT a+5, b*10 FROM (SELECT x*3 AS a, y+10 AS b FROM t1) WHERE a>b;
ds@1952:   **   \                     \_____________ subquery __________/          /
ds@1952:   **    \_____________________ outer query ______________________________/
ds@1952:   **
ds@1952:   ** We look at every expression in the outer query and every place we see
ds@1952:   ** "a" we substitute "x*3" and every place we see "b" we substitute "y+10".
ds@1952:   */
ds@1952:   pList = p->pEList;
ds@1952:   for(i=0; i<pList->nExpr; i++){
ds@1952:     Expr *pExpr;
ds@1952:     if( pList->a[i].zName==0 && (pExpr = pList->a[i].pExpr)->span.z!=0 ){
ds@1952:       pList->a[i].zName = 
ds@1952:              sqlite3DbStrNDup(db, (char*)pExpr->span.z, pExpr->span.n);
ds@1952:     }
ds@1952:   }
ds@1952:   substExprList(db, p->pEList, iParent, pSub->pEList);
ds@1952:   if( isAgg ){
ds@1952:     substExprList(db, p->pGroupBy, iParent, pSub->pEList);
ds@1952:     substExpr(db, p->pHaving, iParent, pSub->pEList);
ds@1952:   }
ds@1952:   if( pSub->pOrderBy ){
ds@1952:     assert( p->pOrderBy==0 );
ds@1952:     p->pOrderBy = pSub->pOrderBy;
ds@1952:     pSub->pOrderBy = 0;
ds@1952:   }else if( p->pOrderBy ){
ds@1952:     substExprList(db, p->pOrderBy, iParent, pSub->pEList);
ds@1952:   }
ds@1952:   if( pSub->pWhere ){
ds@1952:     pWhere = sqlite3ExprDup(db, pSub->pWhere);
ds@1952:   }else{
ds@1952:     pWhere = 0;
ds@1952:   }
ds@1952:   if( subqueryIsAgg ){
ds@1952:     assert( p->pHaving==0 );
ds@1952:     p->pHaving = p->pWhere;
ds@1952:     p->pWhere = pWhere;
ds@1952:     substExpr(db, p->pHaving, iParent, pSub->pEList);
ds@1952:     p->pHaving = sqlite3ExprAnd(db, p->pHaving, 
ds@1952:                                 sqlite3ExprDup(db, pSub->pHaving));
ds@1952:     assert( p->pGroupBy==0 );
ds@1952:     p->pGroupBy = sqlite3ExprListDup(db, pSub->pGroupBy);
ds@1952:   }else{
ds@1952:     substExpr(db, p->pWhere, iParent, pSub->pEList);
ds@1952:     p->pWhere = sqlite3ExprAnd(db, p->pWhere, pWhere);
ds@1952:   }
ds@1952: 
ds@1952:   /* The flattened query is distinct if either the inner or the
ds@1952:   ** outer query is distinct. 
ds@1952:   */
ds@1952:   p->isDistinct = p->isDistinct || pSub->isDistinct;
ds@1952: 
ds@1952:   /*
ds@1952:   ** SELECT ... FROM (SELECT ... LIMIT a OFFSET b) LIMIT x OFFSET y;
ds@1952:   **
ds@1952:   ** One is tempted to try to add a and b to combine the limits.  But this
ds@1952:   ** does not work if either limit is negative.
ds@1952:   */
ds@1952:   if( pSub->pLimit ){
ds@1952:     p->pLimit = pSub->pLimit;
ds@1952:     pSub->pLimit = 0;
ds@1952:   }
ds@1952: 
ds@1952:   /* Finially, delete what is left of the subquery and return
ds@1952:   ** success.
ds@1952:   */
ds@1952:   sqlite3SelectDelete(pSub);
ds@1952:   return 1;
ds@1952: }
ds@1952: #endif /* SQLITE_OMIT_VIEW */
ds@1952: 
ds@1952: /*
ds@1952: ** Analyze the SELECT statement passed in as an argument to see if it
ds@1952: ** is a simple min() or max() query.  If it is and this query can be
ds@1952: ** satisfied using a single seek to the beginning or end of an index,
ds@1952: ** then generate the code for this SELECT and return 1.  If this is not a 
ds@1952: ** simple min() or max() query, then return 0;
ds@1952: **
ds@1952: ** A simply min() or max() query looks like this:
ds@1952: **
ds@1952: **    SELECT min(a) FROM table;
ds@1952: **    SELECT max(a) FROM table;
ds@1952: **
ds@1952: ** The query may have only a single table in its FROM argument.  There
ds@1952: ** can be no GROUP BY or HAVING or WHERE clauses.  The result set must
ds@1952: ** be the min() or max() of a single column of the table.  The column
ds@1952: ** in the min() or max() function must be indexed.
ds@1952: **
ds@1952: ** The parameters to this routine are the same as for sqlite3Select().
ds@1952: ** See the header comment on that routine for additional information.
ds@1952: */
ds@1952: static int simpleMinMaxQuery(Parse *pParse, Select *p, int eDest, int iParm){
ds@1952:   Expr *pExpr;
ds@1952:   int iCol;
ds@1952:   Table *pTab;
ds@1952:   Index *pIdx;
ds@1952:   int base;
ds@1952:   Vdbe *v;
ds@1952:   int seekOp;
ds@1952:   ExprList *pEList, *pList, eList;
ds@1952:   struct ExprList_item eListItem;
ds@1952:   SrcList *pSrc;
ds@1952:   int brk;
ds@1952:   int iDb;
ds@1952: 
ds@1952:   /* Check to see if this query is a simple min() or max() query.  Return
ds@1952:   ** zero if it is  not.
ds@1952:   */
ds@1952:   if( p->pGroupBy || p->pHaving || p->pWhere ) return 0;
ds@1952:   pSrc = p->pSrc;
ds@1952:   if( pSrc->nSrc!=1 ) return 0;
ds@1952:   pEList = p->pEList;
ds@1952:   if( pEList->nExpr!=1 ) return 0;
ds@1952:   pExpr = pEList->a[0].pExpr;
ds@1952:   if( pExpr->op!=TK_AGG_FUNCTION ) return 0;
ds@1952:   pList = pExpr->pList;
ds@1952:   if( pList==0 || pList->nExpr!=1 ) return 0;
ds@1952:   if( pExpr->token.n!=3 ) return 0;
ds@1952:   if( sqlite3StrNICmp((char*)pExpr->token.z,"min",3)==0 ){
ds@1952:     seekOp = OP_Rewind;
ds@1952:   }else if( sqlite3StrNICmp((char*)pExpr->token.z,"max",3)==0 ){
ds@1952:     seekOp = OP_Last;
ds@1952:   }else{
ds@1952:     return 0;
ds@1952:   }
ds@1952:   pExpr = pList->a[0].pExpr;
ds@1952:   if( pExpr->op!=TK_COLUMN ) return 0;
ds@1952:   iCol = pExpr->iColumn;
ds@1952:   pTab = pSrc->a[0].pTab;
ds@1952: 
ds@1952:   /* This optimization cannot be used with virtual tables. */
ds@1952:   if( IsVirtual(pTab) ) return 0;
ds@1952: 
ds@1952:   /* If we get to here, it means the query is of the correct form.
ds@1952:   ** Check to make sure we have an index and make pIdx point to the
ds@1952:   ** appropriate index.  If the min() or max() is on an INTEGER PRIMARY
ds@1952:   ** key column, no index is necessary so set pIdx to NULL.  If no
ds@1952:   ** usable index is found, return 0.
ds@1952:   */
ds@1952:   if( iCol<0 ){
ds@1952:     pIdx = 0;
ds@1952:   }else{
ds@1952:     CollSeq *pColl = sqlite3ExprCollSeq(pParse, pExpr);
ds@1952:     if( pColl==0 ) return 0;
ds@1952:     for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
ds@1952:       assert( pIdx->nColumn>=1 );
ds@1952:       if( pIdx->aiColumn[0]==iCol && 
ds@1952:           0==sqlite3StrICmp(pIdx->azColl[0], pColl->zName) ){
ds@1952:         break;
ds@1952:       }
ds@1952:     }
ds@1952:     if( pIdx==0 ) return 0;
ds@1952:   }
ds@1952: 
ds@1952:   /* Identify column types if we will be using the callback.  This
ds@1952:   ** step is skipped if the output is going to a table or a memory cell.
ds@1952:   ** The column names have already been generated in the calling function.
ds@1952:   */
ds@1952:   v = sqlite3GetVdbe(pParse);
ds@1952:   if( v==0 ) return 0;
ds@1952: 
ds@1952:   /* If the output is destined for a temporary table, open that table.
ds@1952:   */
ds@1952:   if( eDest==SRT_EphemTab ){
ds@1952:     sqlite3VdbeAddOp(v, OP_OpenEphemeral, iParm, 1);
ds@1952:   }
ds@1952: 
ds@1952:   /* Generating code to find the min or the max.  Basically all we have
ds@1952:   ** to do is find the first or the last entry in the chosen index.  If
ds@1952:   ** the min() or max() is on the INTEGER PRIMARY KEY, then find the first
ds@1952:   ** or last entry in the main table.
ds@1952:   */
ds@1952:   iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);
ds@1952:   assert( iDb>=0 || pTab->isEphem );
ds@1952:   sqlite3CodeVerifySchema(pParse, iDb);
ds@1952:   sqlite3TableLock(pParse, iDb, pTab->tnum, 0, pTab->zName);
ds@1952:   base = pSrc->a[0].iCursor;
ds@1952:   brk = sqlite3VdbeMakeLabel(v);
ds@1952:   computeLimitRegisters(pParse, p, brk);
ds@1952:   if( pSrc->a[0].pSelect==0 ){
ds@1952:     sqlite3OpenTable(pParse, base, iDb, pTab, OP_OpenRead);
ds@1952:   }
ds@1952:   if( pIdx==0 ){
ds@1952:     sqlite3VdbeAddOp(v, seekOp, base, 0);
ds@1952:   }else{
ds@1952:     /* Even though the cursor used to open the index here is closed
ds@1952:     ** as soon as a single value has been read from it, allocate it
ds@1952:     ** using (pParse->nTab++) to prevent the cursor id from being 
ds@1952:     ** reused. This is important for statements of the form 
ds@1952:     ** "INSERT INTO x SELECT max() FROM x".
ds@1952:     */
ds@1952:     int iIdx;
ds@1952:     KeyInfo *pKey = sqlite3IndexKeyinfo(pParse, pIdx);
ds@1952:     iIdx = pParse->nTab++;
ds@1952:     assert( pIdx->pSchema==pTab->pSchema );
ds@1952:     sqlite3VdbeAddOp(v, OP_Integer, iDb, 0);
ds@1952:     sqlite3VdbeOp3(v, OP_OpenRead, iIdx, pIdx->tnum, 
ds@1952:         (char*)pKey, P3_KEYINFO_HANDOFF);
ds@1952:     if( seekOp==OP_Rewind ){
ds@1952:       sqlite3VdbeAddOp(v, OP_Null, 0, 0);
ds@1952:       sqlite3VdbeAddOp(v, OP_MakeRecord, 1, 0);
ds@1952:       seekOp = OP_MoveGt;
ds@1952:     }
ds@1952:     if( pIdx->aSortOrder[0]==SQLITE_SO_DESC ){
ds@1952:       /* Ticket #2514: invert the seek operator if we are using
ds@1952:       ** a descending index. */
ds@1952:       if( seekOp==OP_Last ){
ds@1952:         seekOp = OP_Rewind;
ds@1952:       }else{
ds@1952:         assert( seekOp==OP_MoveGt );
ds@1952:         seekOp = OP_MoveLt;
ds@1952:       }
ds@1952:     }
ds@1952:     sqlite3VdbeAddOp(v, seekOp, iIdx, 0);
ds@1952:     sqlite3VdbeAddOp(v, OP_IdxRowid, iIdx, 0);
ds@1952:     sqlite3VdbeAddOp(v, OP_Close, iIdx, 0);
ds@1952:     sqlite3VdbeAddOp(v, OP_MoveGe, base, 0);
ds@1952:   }
ds@1952:   eList.nExpr = 1;
ds@1952:   memset(&eListItem, 0, sizeof(eListItem));
ds@1952:   eList.a = &eListItem;
ds@1952:   eList.a[0].pExpr = pExpr;
ds@1952:   selectInnerLoop(pParse, p, &eList, 0, 0, 0, -1, eDest, iParm, brk, brk, 0);
ds@1952:   sqlite3VdbeResolveLabel(v, brk);
ds@1952:   sqlite3VdbeAddOp(v, OP_Close, base, 0);
ds@1952:   
ds@1952:   return 1;
ds@1952: }
ds@1952: 
ds@1952: /*
ds@1952: ** Analyze and ORDER BY or GROUP BY clause in a SELECT statement.  Return
ds@1952: ** the number of errors seen.
ds@1952: **
ds@1952: ** An ORDER BY or GROUP BY is a list of expressions.  If any expression
ds@1952: ** is an integer constant, then that expression is replaced by the
ds@1952: ** corresponding entry in the result set.
ds@1952: */
ds@1952: static int processOrderGroupBy(
ds@1952:   NameContext *pNC,     /* Name context of the SELECT statement. */
ds@1952:   ExprList *pOrderBy,   /* The ORDER BY or GROUP BY clause to be processed */
ds@1952:   const char *zType     /* Either "ORDER" or "GROUP", as appropriate */
ds@1952: ){
ds@1952:   int i;
ds@1952:   ExprList *pEList = pNC->pEList;     /* The result set of the SELECT */
ds@1952:   Parse *pParse = pNC->pParse;     /* The result set of the SELECT */
ds@1952:   assert( pEList );
ds@1952: 
ds@1952:   if( pOrderBy==0 ) return 0;
ds@1952:   if( pOrderBy->nExpr>SQLITE_MAX_COLUMN ){
ds@1952:     sqlite3ErrorMsg(pParse, "too many terms in %s BY clause", zType);
ds@1952:     return 1;
ds@1952:   }
ds@1952:   for(i=0; i<pOrderBy->nExpr; i++){
ds@1952:     int iCol;
ds@1952:     Expr *pE = pOrderBy->a[i].pExpr;
ds@1952:     if( sqlite3ExprIsInteger(pE, &iCol) ){
ds@1952:       if( iCol>0 && iCol<=pEList->nExpr ){
ds@1952:         CollSeq *pColl = pE->pColl;
ds@1952:         int flags = pE->flags & EP_ExpCollate;
ds@1952:         sqlite3ExprDelete(pE);
ds@1952:         pE = sqlite3ExprDup(pParse->db, pEList->a[iCol-1].pExpr);
ds@1952:         pOrderBy->a[i].pExpr = pE;
ds@1952:         if( pColl && flags ){
ds@1952:           pE->pColl = pColl;
ds@1952:           pE->flags |= flags;
ds@1952:         }
ds@1952:       }else{
ds@1952:         sqlite3ErrorMsg(pParse, 
ds@1952:            "%s BY column number %d out of range - should be "
ds@1952:            "between 1 and %d", zType, iCol, pEList->nExpr);
ds@1952:         return 1;
ds@1952:       }
ds@1952:     }
ds@1952:     if( sqlite3ExprResolveNames(pNC, pE) ){
ds@1952:       return 1;
ds@1952:     }
ds@1952:   }
ds@1952:   return 0;
ds@1952: }
ds@1952: 
ds@1952: /*
ds@1952: ** This routine resolves any names used in the result set of the
ds@1952: ** supplied SELECT statement. If the SELECT statement being resolved
ds@1952: ** is a sub-select, then pOuterNC is a pointer to the NameContext 
ds@1952: ** of the parent SELECT.
ds@1952: */
ds@1952: int sqlite3SelectResolve(
ds@1952:   Parse *pParse,         /* The parser context */
ds@1952:   Select *p,             /* The SELECT statement being coded. */
ds@1952:   NameContext *pOuterNC  /* The outer name context. May be NULL. */
ds@1952: ){
ds@1952:   ExprList *pEList;          /* Result set. */
ds@1952:   int i;                     /* For-loop variable used in multiple places */
ds@1952:   NameContext sNC;           /* Local name-context */
ds@1952:   ExprList *pGroupBy;        /* The group by clause */
ds@1952: 
ds@1952:   /* If this routine has run before, return immediately. */
ds@1952:   if( p->isResolved ){
ds@1952:     assert( !pOuterNC );
ds@1952:     return SQLITE_OK;
ds@1952:   }
ds@1952:   p->isResolved = 1;
ds@1952: 
ds@1952:   /* If there have already been errors, do nothing. */
ds@1952:   if( pParse->nErr>0 ){
ds@1952:     return SQLITE_ERROR;
ds@1952:   }
ds@1952: 
ds@1952:   /* Prepare the select statement. This call will allocate all cursors
ds@1952:   ** required to handle the tables and subqueries in the FROM clause.
ds@1952:   */
ds@1952:   if( prepSelectStmt(pParse, p) ){
ds@1952:     return SQLITE_ERROR;
ds@1952:   }
ds@1952: 
ds@1952:   /* Resolve the expressions in the LIMIT and OFFSET clauses. These
ds@1952:   ** are not allowed to refer to any names, so pass an empty NameContext.
ds@1952:   */
ds@1952:   memset(&sNC, 0, sizeof(sNC));
ds@1952:   sNC.pParse = pParse;
ds@1952:   if( sqlite3ExprResolveNames(&sNC, p->pLimit) ||
ds@1952:       sqlite3ExprResolveNames(&sNC, p->pOffset) ){
ds@1952:     return SQLITE_ERROR;
ds@1952:   }
ds@1952: 
ds@1952:   /* Set up the local name-context to pass to ExprResolveNames() to
ds@1952:   ** resolve the expression-list.
ds@1952:   */
ds@1952:   sNC.allowAgg = 1;
ds@1952:   sNC.pSrcList = p->pSrc;
ds@1952:   sNC.pNext = pOuterNC;
ds@1952: 
ds@1952:   /* Resolve names in the result set. */
ds@1952:   pEList = p->pEList;
ds@1952:   if( !pEList ) return SQLITE_ERROR;
ds@1952:   for(i=0; i<pEList->nExpr; i++){
ds@1952:     Expr *pX = pEList->a[i].pExpr;
ds@1952:     if( sqlite3ExprResolveNames(&sNC, pX) ){
ds@1952:       return SQLITE_ERROR;
ds@1952:     }
ds@1952:   }
ds@1952: 
ds@1952:   /* If there are no aggregate functions in the result-set, and no GROUP BY 
ds@1952:   ** expression, do not allow aggregates in any of the other expressions.
ds@1952:   */
ds@1952:   assert( !p->isAgg );
ds@1952:   pGroupBy = p->pGroupBy;
ds@1952:   if( pGroupBy || sNC.hasAgg ){
ds@1952:     p->isAgg = 1;
ds@1952:   }else{
ds@1952:     sNC.allowAgg = 0;
ds@1952:   }
ds@1952: 
ds@1952:   /* If a HAVING clause is present, then there must be a GROUP BY clause.
ds@1952:   */
ds@1952:   if( p->pHaving && !pGroupBy ){
ds@1952:     sqlite3ErrorMsg(pParse, "a GROUP BY clause is required before HAVING");
ds@1952:     return SQLITE_ERROR;
ds@1952:   }
ds@1952: 
ds@1952:   /* Add the expression list to the name-context before parsing the
ds@1952:   ** other expressions in the SELECT statement. This is so that
ds@1952:   ** expressions in the WHERE clause (etc.) can refer to expressions by
ds@1952:   ** aliases in the result set.
ds@1952:   **
ds@1952:   ** Minor point: If this is the case, then the expression will be
ds@1952:   ** re-evaluated for each reference to it.
ds@1952:   */
ds@1952:   sNC.pEList = p->pEList;
ds@1952:   if( sqlite3ExprResolveNames(&sNC, p->pWhere) ||
ds@1952:      sqlite3ExprResolveNames(&sNC, p->pHaving) ){
ds@1952:     return SQLITE_ERROR;
ds@1952:   }
ds@1952:   if( p->pPrior==0 ){
ds@1952:     if( processOrderGroupBy(&sNC, p->pOrderBy, "ORDER") ||
ds@1952:         processOrderGroupBy(&sNC, pGroupBy, "GROUP") ){
ds@1952:       return SQLITE_ERROR;
ds@1952:     }
ds@1952:   }
ds@1952: 
ds@1952:   if( pParse->db->mallocFailed ){
ds@1952:     return SQLITE_NOMEM;
ds@1952:   }
ds@1952: 
ds@1952:   /* Make sure the GROUP BY clause does not contain aggregate functions.
ds@1952:   */
ds@1952:   if( pGroupBy ){
ds@1952:     struct ExprList_item *pItem;
ds@1952:   
ds@1952:     for(i=0, pItem=pGroupBy->a; i<pGroupBy->nExpr; i++, pItem++){
ds@1952:       if( ExprHasProperty(pItem->pExpr, EP_Agg) ){
ds@1952:         sqlite3ErrorMsg(pParse, "aggregate functions are not allowed in "
ds@1952:             "the GROUP BY clause");
ds@1952:         return SQLITE_ERROR;
ds@1952:       }
ds@1952:     }
ds@1952:   }
ds@1952: 
ds@1952:   /* If this is one SELECT of a compound, be sure to resolve names
ds@1952:   ** in the other SELECTs.
ds@1952:   */
ds@1952:   if( p->pPrior ){
ds@1952:     return sqlite3SelectResolve(pParse, p->pPrior, pOuterNC);
ds@1952:   }else{
ds@1952:     return SQLITE_OK;
ds@1952:   }
ds@1952: }
ds@1952: 
ds@1952: /*
ds@1952: ** Reset the aggregate accumulator.
ds@1952: **
ds@1952: ** The aggregate accumulator is a set of memory cells that hold
ds@1952: ** intermediate results while calculating an aggregate.  This
ds@1952: ** routine simply stores NULLs in all of those memory cells.
ds@1952: */
ds@1952: static void resetAccumulator(Parse *pParse, AggInfo *pAggInfo){
ds@1952:   Vdbe *v = pParse->pVdbe;
ds@1952:   int i;
ds@1952:   struct AggInfo_func *pFunc;
ds@1952:   if( pAggInfo->nFunc+pAggInfo->nColumn==0 ){
ds@1952:     return;
ds@1952:   }
ds@1952:   for(i=0; i<pAggInfo->nColumn; i++){
ds@1952:     sqlite3VdbeAddOp(v, OP_MemNull, pAggInfo->aCol[i].iMem, 0);
ds@1952:   }
ds@1952:   for(pFunc=pAggInfo->aFunc, i=0; i<pAggInfo->nFunc; i++, pFunc++){
ds@1952:     sqlite3VdbeAddOp(v, OP_MemNull, pFunc->iMem, 0);
ds@1952:     if( pFunc->iDistinct>=0 ){
ds@1952:       Expr *pE = pFunc->pExpr;
ds@1952:       if( pE->pList==0 || pE->pList->nExpr!=1 ){
ds@1952:         sqlite3ErrorMsg(pParse, "DISTINCT in aggregate must be followed "
ds@1952:            "by an expression");
ds@1952:         pFunc->iDistinct = -1;
ds@1952:       }else{
ds@1952:         KeyInfo *pKeyInfo = keyInfoFromExprList(pParse, pE->pList);
ds@1952:         sqlite3VdbeOp3(v, OP_OpenEphemeral, pFunc->iDistinct, 0, 
ds@1952:                           (char*)pKeyInfo, P3_KEYINFO_HANDOFF);
ds@1952:       }
ds@1952:     }
ds@1952:   }
ds@1952: }
ds@1952: 
ds@1952: /*
ds@1952: ** Invoke the OP_AggFinalize opcode for every aggregate function
ds@1952: ** in the AggInfo structure.
ds@1952: */
ds@1952: static void finalizeAggFunctions(Parse *pParse, AggInfo *pAggInfo){
ds@1952:   Vdbe *v = pParse->pVdbe;
ds@1952:   int i;
ds@1952:   struct AggInfo_func *pF;
ds@1952:   for(i=0, pF=pAggInfo->aFunc; i<pAggInfo->nFunc; i++, pF++){
ds@1952:     ExprList *pList = pF->pExpr->pList;
ds@1952:     sqlite3VdbeOp3(v, OP_AggFinal, pF->iMem, pList ? pList->nExpr : 0,
ds@1952:                       (void*)pF->pFunc, P3_FUNCDEF);
ds@1952:   }
ds@1952: }
ds@1952: 
ds@1952: /*
ds@1952: ** Update the accumulator memory cells for an aggregate based on
ds@1952: ** the current cursor position.
ds@1952: */
ds@1952: static void updateAccumulator(Parse *pParse, AggInfo *pAggInfo){
ds@1952:   Vdbe *v = pParse->pVdbe;
ds@1952:   int i;
ds@1952:   struct AggInfo_func *pF;
ds@1952:   struct AggInfo_col *pC;
ds@1952: 
ds@1952:   pAggInfo->directMode = 1;
ds@1952:   for(i=0, pF=pAggInfo->aFunc; i<pAggInfo->nFunc; i++, pF++){
ds@1952:     int nArg;
ds@1952:     int addrNext = 0;
ds@1952:     ExprList *pList = pF->pExpr->pList;
ds@1952:     if( pList ){
ds@1952:       nArg = pList->nExpr;
ds@1952:       sqlite3ExprCodeExprList(pParse, pList);
ds@1952:     }else{
ds@1952:       nArg = 0;
ds@1952:     }
ds@1952:     if( pF->iDistinct>=0 ){
ds@1952:       addrNext = sqlite3VdbeMakeLabel(v);
ds@1952:       assert( nArg==1 );
ds@1952:       codeDistinct(v, pF->iDistinct, addrNext, 1);
ds@1952:     }
ds@1952:     if( pF->pFunc->needCollSeq ){
ds@1952:       CollSeq *pColl = 0;
ds@1952:       struct ExprList_item *pItem;
ds@1952:       int j;
ds@1952:       assert( pList!=0 );  /* pList!=0 if pF->pFunc->needCollSeq is true */
ds@1952:       for(j=0, pItem=pList->a; !pColl && j<nArg; j++, pItem++){
ds@1952:         pColl = sqlite3ExprCollSeq(pParse, pItem->pExpr);
ds@1952:       }
ds@1952:       if( !pColl ){
ds@1952:         pColl = pParse->db->pDfltColl;
ds@1952:       }
ds@1952:       sqlite3VdbeOp3(v, OP_CollSeq, 0, 0, (char *)pColl, P3_COLLSEQ);
ds@1952:     }
ds@1952:     sqlite3VdbeOp3(v, OP_AggStep, pF->iMem, nArg, (void*)pF->pFunc, P3_FUNCDEF);
ds@1952:     if( addrNext ){
ds@1952:       sqlite3VdbeResolveLabel(v, addrNext);
ds@1952:     }
ds@1952:   }
ds@1952:   for(i=0, pC=pAggInfo->aCol; i<pAggInfo->nAccumulator; i++, pC++){
ds@1952:     sqlite3ExprCode(pParse, pC->pExpr);
ds@1952:     sqlite3VdbeAddOp(v, OP_MemStore, pC->iMem, 1);
ds@1952:   }
ds@1952:   pAggInfo->directMode = 0;
ds@1952: }
ds@1952: 
ds@1952: 
ds@1952: /*
ds@1952: ** Generate code for the given SELECT statement.
ds@1952: **
ds@1952: ** The results are distributed in various ways depending on the
ds@1952: ** value of eDest and iParm.
ds@1952: **
ds@1952: **     eDest Value       Result
ds@1952: **     ------------    -------------------------------------------
ds@1952: **     SRT_Callback    Invoke the callback for each row of the result.
ds@1952: **
ds@1952: **     SRT_Mem         Store first result in memory cell iParm
ds@1952: **
ds@1952: **     SRT_Set         Store results as keys of table iParm.
ds@1952: **
ds@1952: **     SRT_Union       Store results as a key in a temporary table iParm
ds@1952: **
ds@1952: **     SRT_Except      Remove results from the temporary table iParm.
ds@1952: **
ds@1952: **     SRT_Table       Store results in temporary table iParm
ds@1952: **
ds@1952: ** The table above is incomplete.  Additional eDist value have be added
ds@1952: ** since this comment was written.  See the selectInnerLoop() function for
ds@1952: ** a complete listing of the allowed values of eDest and their meanings.
ds@1952: **
ds@1952: ** This routine returns the number of errors.  If any errors are
ds@1952: ** encountered, then an appropriate error message is left in
ds@1952: ** pParse->zErrMsg.
ds@1952: **
ds@1952: ** This routine does NOT free the Select structure passed in.  The
ds@1952: ** calling function needs to do that.
ds@1952: **
ds@1952: ** The pParent, parentTab, and *pParentAgg fields are filled in if this
ds@1952: ** SELECT is a subquery.  This routine may try to combine this SELECT
ds@1952: ** with its parent to form a single flat query.  In so doing, it might
ds@1952: ** change the parent query from a non-aggregate to an aggregate query.
ds@1952: ** For that reason, the pParentAgg flag is passed as a pointer, so it
ds@1952: ** can be changed.
ds@1952: **
ds@1952: ** Example 1:   The meaning of the pParent parameter.
ds@1952: **
ds@1952: **    SELECT * FROM t1 JOIN (SELECT x, count(*) FROM t2) JOIN t3;
ds@1952: **    \                      \_______ subquery _______/        /
ds@1952: **     \                                                      /
ds@1952: **      \____________________ outer query ___________________/
ds@1952: **
ds@1952: ** This routine is called for the outer query first.   For that call,
ds@1952: ** pParent will be NULL.  During the processing of the outer query, this 
ds@1952: ** routine is called recursively to handle the subquery.  For the recursive
ds@1952: ** call, pParent will point to the outer query.  Because the subquery is
ds@1952: ** the second element in a three-way join, the parentTab parameter will
ds@1952: ** be 1 (the 2nd value of a 0-indexed array.)
ds@1952: */
ds@1952: int sqlite3Select(
ds@1952:   Parse *pParse,         /* The parser context */
ds@1952:   Select *p,             /* The SELECT statement being coded. */
ds@1952:   int eDest,             /* How to dispose of the results */
ds@1952:   int iParm,             /* A parameter used by the eDest disposal method */
ds@1952:   Select *pParent,       /* Another SELECT for which this is a sub-query */
ds@1952:   int parentTab,         /* Index in pParent->pSrc of this query */
ds@1952:   int *pParentAgg,       /* True if pParent uses aggregate functions */
ds@1952:   char *aff              /* If eDest is SRT_Union, the affinity string */
ds@1952: ){
ds@1952:   int i, j;              /* Loop counters */
ds@1952:   WhereInfo *pWInfo;     /* Return from sqlite3WhereBegin() */
ds@1952:   Vdbe *v;               /* The virtual machine under construction */
ds@1952:   int isAgg;             /* True for select lists like "count(*)" */
ds@1952:   ExprList *pEList;      /* List of columns to extract. */
ds@1952:   SrcList *pTabList;     /* List of tables to select from */
ds@1952:   Expr *pWhere;          /* The WHERE clause.  May be NULL */
ds@1952:   ExprList *pOrderBy;    /* The ORDER BY clause.  May be NULL */
ds@1952:   ExprList *pGroupBy;    /* The GROUP BY clause.  May be NULL */
ds@1952:   Expr *pHaving;         /* The HAVING clause.  May be NULL */
ds@1952:   int isDistinct;        /* True if the DISTINCT keyword is present */
ds@1952:   int distinct;          /* Table to use for the distinct set */
ds@1952:   int rc = 1;            /* Value to return from this function */
ds@1952:   int addrSortIndex;     /* Address of an OP_OpenEphemeral instruction */
ds@1952:   AggInfo sAggInfo;      /* Information used by aggregate queries */
ds@1952:   int iEnd;              /* Address of the end of the query */
ds@1952:   sqlite3 *db;           /* The database connection */
ds@1952: 
ds@1952:   db = pParse->db;
ds@1952:   if( p==0 || db->mallocFailed || pParse->nErr ){
ds@1952:     return 1;
ds@1952:   }
ds@1952:   if( sqlite3AuthCheck(pParse, SQLITE_SELECT, 0, 0, 0) ) return 1;
ds@1952:   memset(&sAggInfo, 0, sizeof(sAggInfo));
ds@1952: 
ds@1952: #ifndef SQLITE_OMIT_COMPOUND_SELECT
ds@1952:   /* If there is are a sequence of queries, do the earlier ones first.
ds@1952:   */
ds@1952:   if( p->pPrior ){
ds@1952:     if( p->pRightmost==0 ){
ds@1952:       Select *pLoop;
ds@1952:       int cnt = 0;
ds@1952:       for(pLoop=p; pLoop; pLoop=pLoop->pPrior, cnt++){
ds@1952:         pLoop->pRightmost = p;
ds@1952:       }
ds@1952:       if( SQLITE_MAX_COMPOUND_SELECT>0 && cnt>SQLITE_MAX_COMPOUND_SELECT ){
ds@1952:         sqlite3ErrorMsg(pParse, "too many terms in compound SELECT");
ds@1952:         return 1;
ds@1952:       }
ds@1952:     }
ds@1952:     return multiSelect(pParse, p, eDest, iParm, aff);
ds@1952:   }
ds@1952: #endif
ds@1952: 
ds@1952:   pOrderBy = p->pOrderBy;
ds@1952:   if( IgnorableOrderby(eDest) ){
ds@1952:     p->pOrderBy = 0;
ds@1952:   }
ds@1952:   if( sqlite3SelectResolve(pParse, p, 0) ){
ds@1952:     goto select_end;
ds@1952:   }
ds@1952:   p->pOrderBy = pOrderBy;
ds@1952: 
ds@1952:   /* Make local copies of the parameters for this query.
ds@1952:   */
ds@1952:   pTabList = p->pSrc;
ds@1952:   pWhere = p->pWhere;
ds@1952:   pGroupBy = p->pGroupBy;
ds@1952:   pHaving = p->pHaving;
ds@1952:   isAgg = p->isAgg;
ds@1952:   isDistinct = p->isDistinct;
ds@1952:   pEList = p->pEList;
ds@1952:   if( pEList==0 ) goto select_end;
ds@1952: 
ds@1952:   /* 
ds@1952:   ** Do not even attempt to generate any code if we have already seen
ds@1952:   ** errors before this routine starts.
ds@1952:   */
ds@1952:   if( pParse->nErr>0 ) goto select_end;
ds@1952: 
ds@1952:   /* If writing to memory or generating a set
ds@1952:   ** only a single column may be output.
ds@1952:   */
ds@1952: #ifndef SQLITE_OMIT_SUBQUERY
ds@1952:   if( checkForMultiColumnSelectError(pParse, eDest, pEList->nExpr) ){
ds@1952:     goto select_end;
ds@1952:   }
ds@1952: #endif
ds@1952: 
ds@1952:   /* ORDER BY is ignored for some destinations.
ds@1952:   */
ds@1952:   if( IgnorableOrderby(eDest) ){
ds@1952:     pOrderBy = 0;
ds@1952:   }
ds@1952: 
ds@1952:   /* Begin generating code.
ds@1952:   */
ds@1952:   v = sqlite3GetVdbe(pParse);
ds@1952:   if( v==0 ) goto select_end;
ds@1952: 
ds@1952:   /* Generate code for all sub-queries in the FROM clause
ds@1952:   */
ds@1952: #if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW)
ds@1952:   for(i=0; i<pTabList->nSrc; i++){
ds@1952:     const char *zSavedAuthContext = 0;
ds@1952:     int needRestoreContext;
ds@1952:     struct SrcList_item *pItem = &pTabList->a[i];
ds@1952: 
ds@1952:     if( pItem->pSelect==0 || pItem->isPopulated ) continue;
ds@1952:     if( pItem->zName!=0 ){
ds@1952:       zSavedAuthContext = pParse->zAuthContext;
ds@1952:       pParse->zAuthContext = pItem->zName;
ds@1952:       needRestoreContext = 1;
ds@1952:     }else{
ds@1952:       needRestoreContext = 0;
ds@1952:     }
ds@1952: #if defined(SQLITE_TEST) || SQLITE_MAX_EXPR_DEPTH>0
ds@1952:     /* Increment Parse.nHeight by the height of the largest expression
ds@1952:     ** tree refered to by this, the parent select. The child select
ds@1952:     ** may contain expression trees of at most
ds@1952:     ** (SQLITE_MAX_EXPR_DEPTH-Parse.nHeight) height. This is a bit
ds@1952:     ** more conservative than necessary, but much easier than enforcing
ds@1952:     ** an exact limit.
ds@1952:     */
ds@1952:     pParse->nHeight += sqlite3SelectExprHeight(p);
ds@1952: #endif
ds@1952:     sqlite3Select(pParse, pItem->pSelect, SRT_EphemTab, 
ds@1952:                  pItem->iCursor, p, i, &isAgg, 0);
ds@1952: #if defined(SQLITE_TEST) || SQLITE_MAX_EXPR_DEPTH>0
ds@1952:     pParse->nHeight -= sqlite3SelectExprHeight(p);
ds@1952: #endif
ds@1952:     if( needRestoreContext ){
ds@1952:       pParse->zAuthContext = zSavedAuthContext;
ds@1952:     }
ds@1952:     pTabList = p->pSrc;
ds@1952:     pWhere = p->pWhere;
ds@1952:     if( !IgnorableOrderby(eDest) ){
ds@1952:       pOrderBy = p->pOrderBy;
ds@1952:     }
ds@1952:     pGroupBy = p->pGroupBy;
ds@1952:     pHaving = p->pHaving;
ds@1952:     isDistinct = p->isDistinct;
ds@1952:   }
ds@1952: #endif
ds@1952: 
ds@1952:   /* Check for the special case of a min() or max() function by itself
ds@1952:   ** in the result set.
ds@1952:   */
ds@1952:   if( simpleMinMaxQuery(pParse, p, eDest, iParm) ){
ds@1952:     rc = 0;
ds@1952:     goto select_end;
ds@1952:   }
ds@1952: 
ds@1952:   /* Check to see if this is a subquery that can be "flattened" into its parent.
ds@1952:   ** If flattening is a possiblity, do so and return immediately.  
ds@1952:   */
ds@1952: #ifndef SQLITE_OMIT_VIEW
ds@1952:   if( pParent && pParentAgg &&
ds@1952:       flattenSubquery(db, pParent, parentTab, *pParentAgg, isAgg) ){
ds@1952:     if( isAgg ) *pParentAgg = 1;
ds@1952:     goto select_end;
ds@1952:   }
ds@1952: #endif
ds@1952: 
ds@1952:   /* If there is an ORDER BY clause, then this sorting
ds@1952:   ** index might end up being unused if the data can be 
ds@1952:   ** extracted in pre-sorted order.  If that is the case, then the
ds@1952:   ** OP_OpenEphemeral instruction will be changed to an OP_Noop once
ds@1952:   ** we figure out that the sorting index is not needed.  The addrSortIndex
ds@1952:   ** variable is used to facilitate that change.
ds@1952:   */
ds@1952:   if( pOrderBy ){
ds@1952:     KeyInfo *pKeyInfo;
ds@1952:     if( pParse->nErr ){
ds@1952:       goto select_end;
ds@1952:     }
ds@1952:     pKeyInfo = keyInfoFromExprList(pParse, pOrderBy);
ds@1952:     pOrderBy->iECursor = pParse->nTab++;
ds@1952:     p->addrOpenEphm[2] = addrSortIndex =
ds@1952:       sqlite3VdbeOp3(v, OP_OpenEphemeral, pOrderBy->iECursor, pOrderBy->nExpr+2,                     (char*)pKeyInfo, P3_KEYINFO_HANDOFF);
ds@1952:   }else{
ds@1952:     addrSortIndex = -1;
ds@1952:   }
ds@1952: 
ds@1952:   /* If the output is destined for a temporary table, open that table.
ds@1952:   */
ds@1952:   if( eDest==SRT_EphemTab ){
ds@1952:     sqlite3VdbeAddOp(v, OP_OpenEphemeral, iParm, pEList->nExpr);
ds@1952:   }
ds@1952: 
ds@1952:   /* Set the limiter.
ds@1952:   */
ds@1952:   iEnd = sqlite3VdbeMakeLabel(v);
ds@1952:   computeLimitRegisters(pParse, p, iEnd);
ds@1952: 
ds@1952:   /* Open a virtual index to use for the distinct set.
ds@1952:   */
ds@1952:   if( isDistinct ){
ds@1952:     KeyInfo *pKeyInfo;
ds@1952:     distinct = pParse->nTab++;
ds@1952:     pKeyInfo = keyInfoFromExprList(pParse, p->pEList);
ds@1952:     sqlite3VdbeOp3(v, OP_OpenEphemeral, distinct, 0, 
ds@1952:                         (char*)pKeyInfo, P3_KEYINFO_HANDOFF);
ds@1952:   }else{
ds@1952:     distinct = -1;
ds@1952:   }
ds@1952: 
ds@1952:   /* Aggregate and non-aggregate queries are handled differently */
ds@1952:   if( !isAgg && pGroupBy==0 ){
ds@1952:     /* This case is for non-aggregate queries
ds@1952:     ** Begin the database scan
ds@1952:     */
ds@1952:     pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, &pOrderBy);
ds@1952:     if( pWInfo==0 ) goto select_end;
ds@1952: 
ds@1952:     /* If sorting index that was created by a prior OP_OpenEphemeral 
ds@1952:     ** instruction ended up not being needed, then change the OP_OpenEphemeral
ds@1952:     ** into an OP_Noop.
ds@1952:     */
ds@1952:     if( addrSortIndex>=0 && pOrderBy==0 ){
ds@1952:       sqlite3VdbeChangeToNoop(v, addrSortIndex, 1);
ds@1952:       p->addrOpenEphm[2] = -1;
ds@1952:     }
ds@1952: 
ds@1952:     /* Use the standard inner loop
ds@1952:     */
ds@1952:     if( selectInnerLoop(pParse, p, pEList, 0, 0, pOrderBy, distinct, eDest,
ds@1952:                     iParm, pWInfo->iContinue, pWInfo->iBreak, aff) ){
ds@1952:        goto select_end;
ds@1952:     }
ds@1952: 
ds@1952:     /* End the database scan loop.
ds@1952:     */
ds@1952:     sqlite3WhereEnd(pWInfo);
ds@1952:   }else{
ds@1952:     /* This is the processing for aggregate queries */
ds@1952:     NameContext sNC;    /* Name context for processing aggregate information */
ds@1952:     int iAMem;          /* First Mem address for storing current GROUP BY */
ds@1952:     int iBMem;          /* First Mem address for previous GROUP BY */
ds@1952:     int iUseFlag;       /* Mem address holding flag indicating that at least
ds@1952:                         ** one row of the input to the aggregator has been
ds@1952:                         ** processed */
ds@1952:     int iAbortFlag;     /* Mem address which causes query abort if positive */
ds@1952:     int groupBySort;    /* Rows come from source in GROUP BY order */
ds@1952: 
ds@1952: 
ds@1952:     /* The following variables hold addresses or labels for parts of the
ds@1952:     ** virtual machine program we are putting together */
ds@1952:     int addrOutputRow;      /* Start of subroutine that outputs a result row */
ds@1952:     int addrSetAbort;       /* Set the abort flag and return */
ds@1952:     int addrInitializeLoop; /* Start of code that initializes the input loop */
ds@1952:     int addrTopOfLoop;      /* Top of the input loop */
ds@1952:     int addrGroupByChange;  /* Code that runs when any GROUP BY term changes */
ds@1952:     int addrProcessRow;     /* Code to process a single input row */
ds@1952:     int addrEnd;            /* End of all processing */
ds@1952:     int addrSortingIdx;     /* The OP_OpenEphemeral for the sorting index */
ds@1952:     int addrReset;          /* Subroutine for resetting the accumulator */
ds@1952: 
ds@1952:     addrEnd = sqlite3VdbeMakeLabel(v);
ds@1952: 
ds@1952:     /* Convert TK_COLUMN nodes into TK_AGG_COLUMN and make entries in
ds@1952:     ** sAggInfo for all TK_AGG_FUNCTION nodes in expressions of the
ds@1952:     ** SELECT statement.
ds@1952:     */
ds@1952:     memset(&sNC, 0, sizeof(sNC));
ds@1952:     sNC.pParse = pParse;
ds@1952:     sNC.pSrcList = pTabList;
ds@1952:     sNC.pAggInfo = &sAggInfo;
ds@1952:     sAggInfo.nSortingColumn = pGroupBy ? pGroupBy->nExpr+1 : 0;
ds@1952:     sAggInfo.pGroupBy = pGroupBy;
ds@1952:     if( sqlite3ExprAnalyzeAggList(&sNC, pEList) ){
ds@1952:       goto select_end;
ds@1952:     }
ds@1952:     if( sqlite3ExprAnalyzeAggList(&sNC, pOrderBy) ){
ds@1952:       goto select_end;
ds@1952:     }
ds@1952:     if( pHaving && sqlite3ExprAnalyzeAggregates(&sNC, pHaving) ){
ds@1952:       goto select_end;
ds@1952:     }
ds@1952:     sAggInfo.nAccumulator = sAggInfo.nColumn;
ds@1952:     for(i=0; i<sAggInfo.nFunc; i++){
ds@1952:       if( sqlite3ExprAnalyzeAggList(&sNC, sAggInfo.aFunc[i].pExpr->pList) ){
ds@1952:         goto select_end;
ds@1952:       }
ds@1952:     }
ds@1952:     if( db->mallocFailed ) goto select_end;
ds@1952: 
ds@1952:     /* Processing for aggregates with GROUP BY is very different and
ds@1952:     ** much more complex tha aggregates without a GROUP BY.
ds@1952:     */
ds@1952:     if( pGroupBy ){
ds@1952:       KeyInfo *pKeyInfo;  /* Keying information for the group by clause */
ds@1952: 
ds@1952:       /* Create labels that we will be needing
ds@1952:       */
ds@1952:      
ds@1952:       addrInitializeLoop = sqlite3VdbeMakeLabel(v);
ds@1952:       addrGroupByChange = sqlite3VdbeMakeLabel(v);
ds@1952:       addrProcessRow = sqlite3VdbeMakeLabel(v);
ds@1952: 
ds@1952:       /* If there is a GROUP BY clause we might need a sorting index to
ds@1952:       ** implement it.  Allocate that sorting index now.  If it turns out
ds@1952:       ** that we do not need it after all, the OpenEphemeral instruction
ds@1952:       ** will be converted into a Noop.  
ds@1952:       */
ds@1952:       sAggInfo.sortingIdx = pParse->nTab++;
ds@1952:       pKeyInfo = keyInfoFromExprList(pParse, pGroupBy);
ds@1952:       addrSortingIdx =
ds@1952:           sqlite3VdbeOp3(v, OP_OpenEphemeral, sAggInfo.sortingIdx,
ds@1952:                          sAggInfo.nSortingColumn,
ds@1952:                          (char*)pKeyInfo, P3_KEYINFO_HANDOFF);
ds@1952: 
ds@1952:       /* Initialize memory locations used by GROUP BY aggregate processing
ds@1952:       */
ds@1952:       iUseFlag = pParse->nMem++;
ds@1952:       iAbortFlag = pParse->nMem++;
ds@1952:       iAMem = pParse->nMem;
ds@1952:       pParse->nMem += pGroupBy->nExpr;
ds@1952:       iBMem = pParse->nMem;
ds@1952:       pParse->nMem += pGroupBy->nExpr;
ds@1952:       sqlite3VdbeAddOp(v, OP_MemInt, 0, iAbortFlag);
ds@1952:       VdbeComment((v, "# clear abort flag"));
ds@1952:       sqlite3VdbeAddOp(v, OP_MemInt, 0, iUseFlag);
ds@1952:       VdbeComment((v, "# indicate accumulator empty"));
ds@1952:       sqlite3VdbeAddOp(v, OP_Goto, 0, addrInitializeLoop);
ds@1952: 
ds@1952:       /* Generate a subroutine that outputs a single row of the result
ds@1952:       ** set.  This subroutine first looks at the iUseFlag.  If iUseFlag
ds@1952:       ** is less than or equal to zero, the subroutine is a no-op.  If
ds@1952:       ** the processing calls for the query to abort, this subroutine
ds@1952:       ** increments the iAbortFlag memory location before returning in
ds@1952:       ** order to signal the caller to abort.
ds@1952:       */
ds@1952:       addrSetAbort = sqlite3VdbeCurrentAddr(v);
ds@1952:       sqlite3VdbeAddOp(v, OP_MemInt, 1, iAbortFlag);
ds@1952:       VdbeComment((v, "# set abort flag"));
ds@1952:       sqlite3VdbeAddOp(v, OP_Return, 0, 0);
ds@1952:       addrOutputRow = sqlite3VdbeCurrentAddr(v);
ds@1952:       sqlite3VdbeAddOp(v, OP_IfMemPos, iUseFlag, addrOutputRow+2);
ds@1952:       VdbeComment((v, "# Groupby result generator entry point"));
ds@1952:       sqlite3VdbeAddOp(v, OP_Return, 0, 0);
ds@1952:       finalizeAggFunctions(pParse, &sAggInfo);
ds@1952:       if( pHaving ){
ds@1952:         sqlite3ExprIfFalse(pParse, pHaving, addrOutputRow+1, 1);
ds@1952:       }
ds@1952:       rc = selectInnerLoop(pParse, p, p->pEList, 0, 0, pOrderBy,
ds@1952:                            distinct, eDest, iParm, 
ds@1952:                            addrOutputRow+1, addrSetAbort, aff);
ds@1952:       if( rc ){
ds@1952:         goto select_end;
ds@1952:       }
ds@1952:       sqlite3VdbeAddOp(v, OP_Return, 0, 0);
ds@1952:       VdbeComment((v, "# end groupby result generator"));
ds@1952: 
ds@1952:       /* Generate a subroutine that will reset the group-by accumulator
ds@1952:       */
ds@1952:       addrReset = sqlite3VdbeCurrentAddr(v);
ds@1952:       resetAccumulator(pParse, &sAggInfo);
ds@1952:       sqlite3VdbeAddOp(v, OP_Return, 0, 0);
ds@1952: 
ds@1952:       /* Begin a loop that will extract all source rows in GROUP BY order.
ds@1952:       ** This might involve two separate loops with an OP_Sort in between, or
ds@1952:       ** it might be a single loop that uses an index to extract information
ds@1952:       ** in the right order to begin with.
ds@1952:       */
ds@1952:       sqlite3VdbeResolveLabel(v, addrInitializeLoop);
ds@1952:       sqlite3VdbeAddOp(v, OP_Gosub, 0, addrReset);
ds@1952:       pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, &pGroupBy);
ds@1952:       if( pWInfo==0 ) goto select_end;
ds@1952:       if( pGroupBy==0 ){
ds@1952:         /* The optimizer is able to deliver rows in group by order so
ds@1952:         ** we do not have to sort.  The OP_OpenEphemeral table will be
ds@1952:         ** cancelled later because we still need to use the pKeyInfo
ds@1952:         */
ds@1952:         pGroupBy = p->pGroupBy;
ds@1952:         groupBySort = 0;
ds@1952:       }else{
ds@1952:         /* Rows are coming out in undetermined order.  We have to push
ds@1952:         ** each row into a sorting index, terminate the first loop,
ds@1952:         ** then loop over the sorting index in order to get the output
ds@1952:         ** in sorted order
ds@1952:         */
ds@1952:         groupBySort = 1;
ds@1952:         sqlite3ExprCodeExprList(pParse, pGroupBy);
ds@1952:         sqlite3VdbeAddOp(v, OP_Sequence, sAggInfo.sortingIdx, 0);
ds@1952:         j = pGroupBy->nExpr+1;
ds@1952:         for(i=0; i<sAggInfo.nColumn; i++){
ds@1952:           struct AggInfo_col *pCol = &sAggInfo.aCol[i];
ds@1952:           if( pCol->iSorterColumn<j ) continue;
ds@1952:           sqlite3ExprCodeGetColumn(v, pCol->pTab, pCol->iColumn, pCol->iTable);
ds@1952:           j++;
ds@1952:         }
ds@1952:         sqlite3VdbeAddOp(v, OP_MakeRecord, j, 0);
ds@1952:         sqlite3VdbeAddOp(v, OP_IdxInsert, sAggInfo.sortingIdx, 0);
ds@1952:         sqlite3WhereEnd(pWInfo);
ds@1952:         sqlite3VdbeAddOp(v, OP_Sort, sAggInfo.sortingIdx, addrEnd);
ds@1952:         VdbeComment((v, "# GROUP BY sort"));
ds@1952:         sAggInfo.useSortingIdx = 1;
ds@1952:       }
ds@1952: 
ds@1952:       /* Evaluate the current GROUP BY terms and store in b0, b1, b2...
ds@1952:       ** (b0 is memory location iBMem+0, b1 is iBMem+1, and so forth)
ds@1952:       ** Then compare the current GROUP BY terms against the GROUP BY terms
ds@1952:       ** from the previous row currently stored in a0, a1, a2...
ds@1952:       */
ds@1952:       addrTopOfLoop = sqlite3VdbeCurrentAddr(v);
ds@1952:       for(j=0; j<pGroupBy->nExpr; j++){
ds@1952:         if( groupBySort ){
ds@1952:           sqlite3VdbeAddOp(v, OP_Column, sAggInfo.sortingIdx, j);
ds@1952:         }else{
ds@1952:           sAggInfo.directMode = 1;
ds@1952:           sqlite3ExprCode(pParse, pGroupBy->a[j].pExpr);
ds@1952:         }
ds@1952:         sqlite3VdbeAddOp(v, OP_MemStore, iBMem+j, j<pGroupBy->nExpr-1);
ds@1952:       }
ds@1952:       for(j=pGroupBy->nExpr-1; j>=0; j--){
ds@1952:         if( j<pGroupBy->nExpr-1 ){
ds@1952:           sqlite3VdbeAddOp(v, OP_MemLoad, iBMem+j, 0);
ds@1952:         }
ds@1952:         sqlite3VdbeAddOp(v, OP_MemLoad, iAMem+j, 0);
ds@1952:         if( j==0 ){
ds@1952:           sqlite3VdbeAddOp(v, OP_Eq, 0x200, addrProcessRow);
ds@1952:         }else{
ds@1952:           sqlite3VdbeAddOp(v, OP_Ne, 0x200, addrGroupByChange);
ds@1952:         }
ds@1952:         sqlite3VdbeChangeP3(v, -1, (void*)pKeyInfo->aColl[j], P3_COLLSEQ);
ds@1952:       }
ds@1952: 
ds@1952:       /* Generate code that runs whenever the GROUP BY changes.
ds@1952:       ** Change in the GROUP BY are detected by the previous code
ds@1952:       ** block.  If there were no changes, this block is skipped.
ds@1952:       **
ds@1952:       ** This code copies current group by terms in b0,b1,b2,...
ds@1952:       ** over to a0,a1,a2.  It then calls the output subroutine
ds@1952:       ** and resets the aggregate accumulator registers in preparation
ds@1952:       ** for the next GROUP BY batch.
ds@1952:       */
ds@1952:       sqlite3VdbeResolveLabel(v, addrGroupByChange);
ds@1952:       for(j=0; j<pGroupBy->nExpr; j++){
ds@1952:         sqlite3VdbeAddOp(v, OP_MemMove, iAMem+j, iBMem+j);
ds@1952:       }
ds@1952:       sqlite3VdbeAddOp(v, OP_Gosub, 0, addrOutputRow);
ds@1952:       VdbeComment((v, "# output one row"));
ds@1952:       sqlite3VdbeAddOp(v, OP_IfMemPos, iAbortFlag, addrEnd);
ds@1952:       VdbeComment((v, "# check abort flag"));
ds@1952:       sqlite3VdbeAddOp(v, OP_Gosub, 0, addrReset);
ds@1952:       VdbeComment((v, "# reset accumulator"));
ds@1952: 
ds@1952:       /* Update the aggregate accumulators based on the content of
ds@1952:       ** the current row
ds@1952:       */
ds@1952:       sqlite3VdbeResolveLabel(v, addrProcessRow);
ds@1952:       updateAccumulator(pParse, &sAggInfo);
ds@1952:       sqlite3VdbeAddOp(v, OP_MemInt, 1, iUseFlag);
ds@1952:       VdbeComment((v, "# indicate data in accumulator"));
ds@1952: 
ds@1952:       /* End of the loop
ds@1952:       */
ds@1952:       if( groupBySort ){
ds@1952:         sqlite3VdbeAddOp(v, OP_Next, sAggInfo.sortingIdx, addrTopOfLoop);
ds@1952:       }else{
ds@1952:         sqlite3WhereEnd(pWInfo);
ds@1952:         sqlite3VdbeChangeToNoop(v, addrSortingIdx, 1);
ds@1952:       }
ds@1952: 
ds@1952:       /* Output the final row of result
ds@1952:       */
ds@1952:       sqlite3VdbeAddOp(v, OP_Gosub, 0, addrOutputRow);
ds@1952:       VdbeComment((v, "# output final row"));
ds@1952:       
ds@1952:     } /* endif pGroupBy */
ds@1952:     else {
ds@1952:       /* This case runs if the aggregate has no GROUP BY clause.  The
ds@1952:       ** processing is much simpler since there is only a single row
ds@1952:       ** of output.
ds@1952:       */
ds@1952:       resetAccumulator(pParse, &sAggInfo);
ds@1952:       pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, 0);
ds@1952:       if( pWInfo==0 ) goto select_end;
ds@1952:       updateAccumulator(pParse, &sAggInfo);
ds@1952:       sqlite3WhereEnd(pWInfo);
ds@1952:       finalizeAggFunctions(pParse, &sAggInfo);
ds@1952:       pOrderBy = 0;
ds@1952:       if( pHaving ){
ds@1952:         sqlite3ExprIfFalse(pParse, pHaving, addrEnd, 1);
ds@1952:       }
ds@1952:       selectInnerLoop(pParse, p, p->pEList, 0, 0, 0, -1, 
ds@1952:                       eDest, iParm, addrEnd, addrEnd, aff);
ds@1952:     }
ds@1952:     sqlite3VdbeResolveLabel(v, addrEnd);
ds@1952:     
ds@1952:   } /* endif aggregate query */
ds@1952: 
ds@1952:   /* If there is an ORDER BY clause, then we need to sort the results
ds@1952:   ** and send them to the callback one by one.
ds@1952:   */
ds@1952:   if( pOrderBy ){
ds@1952:     generateSortTail(pParse, p, v, pEList->nExpr, eDest, iParm);
ds@1952:   }
ds@1952: 
ds@1952: #ifndef SQLITE_OMIT_SUBQUERY
ds@1952:   /* If this was a subquery, we have now converted the subquery into a
ds@1952:   ** temporary table.  So set the SrcList_item.isPopulated flag to prevent
ds@1952:   ** this subquery from being evaluated again and to force the use of
ds@1952:   ** the temporary table.
ds@1952:   */
ds@1952:   if( pParent ){
ds@1952:     assert( pParent->pSrc->nSrc>parentTab );
ds@1952:     assert( pParent->pSrc->a[parentTab].pSelect==p );
ds@1952:     pParent->pSrc->a[parentTab].isPopulated = 1;
ds@1952:   }
ds@1952: #endif
ds@1952: 
ds@1952:   /* Jump here to skip this query
ds@1952:   */
ds@1952:   sqlite3VdbeResolveLabel(v, iEnd);
ds@1952: 
ds@1952:   /* The SELECT was successfully coded.   Set the return code to 0
ds@1952:   ** to indicate no errors.
ds@1952:   */
ds@1952:   rc = 0;
ds@1952: 
ds@1952:   /* Control jumps to here if an error is encountered above, or upon
ds@1952:   ** successful coding of the SELECT.
ds@1952:   */
ds@1952: select_end:
ds@1952: 
ds@1952:   /* Identify column names if we will be using them in a callback.  This
ds@1952:   ** step is skipped if the output is going to some other destination.
ds@1952:   */
ds@1952:   if( rc==SQLITE_OK && eDest==SRT_Callback ){
ds@1952:     generateColumnNames(pParse, pTabList, pEList);
ds@1952:   }
ds@1952: 
ds@1952:   sqlite3_free(sAggInfo.aCol);
ds@1952:   sqlite3_free(sAggInfo.aFunc);
ds@1952:   return rc;
ds@1952: }
ds@1952: 
ds@1952: #if defined(SQLITE_DEBUG)
ds@1952: /*
ds@1952: *******************************************************************************
ds@1952: ** The following code is used for testing and debugging only.  The code
ds@1952: ** that follows does not appear in normal builds.
ds@1952: **
ds@1952: ** These routines are used to print out the content of all or part of a 
ds@1952: ** parse structures such as Select or Expr.  Such printouts are useful
ds@1952: ** for helping to understand what is happening inside the code generator
ds@1952: ** during the execution of complex SELECT statements.
ds@1952: **
ds@1952: ** These routine are not called anywhere from within the normal
ds@1952: ** code base.  Then are intended to be called from within the debugger
ds@1952: ** or from temporary "printf" statements inserted for debugging.
ds@1952: */
ds@1952: void sqlite3PrintExpr(Expr *p){
ds@1952:   if( p->token.z && p->token.n>0 ){
ds@1952:     sqlite3DebugPrintf("(%.*s", p->token.n, p->token.z);
ds@1952:   }else{
ds@1952:     sqlite3DebugPrintf("(%d", p->op);
ds@1952:   }
ds@1952:   if( p->pLeft ){
ds@1952:     sqlite3DebugPrintf(" ");
ds@1952:     sqlite3PrintExpr(p->pLeft);
ds@1952:   }
ds@1952:   if( p->pRight ){
ds@1952:     sqlite3DebugPrintf(" ");
ds@1952:     sqlite3PrintExpr(p->pRight);
ds@1952:   }
ds@1952:   sqlite3DebugPrintf(")");
ds@1952: }
ds@1952: void sqlite3PrintExprList(ExprList *pList){
ds@1952:   int i;
ds@1952:   for(i=0; i<pList->nExpr; i++){
ds@1952:     sqlite3PrintExpr(pList->a[i].pExpr);
ds@1952:     if( i<pList->nExpr-1 ){
ds@1952:       sqlite3DebugPrintf(", ");
ds@1952:     }
ds@1952:   }
ds@1952: }
ds@1952: void sqlite3PrintSelect(Select *p, int indent){
ds@1952:   sqlite3DebugPrintf("%*sSELECT(%p) ", indent, "", p);
ds@1952:   sqlite3PrintExprList(p->pEList);
ds@1952:   sqlite3DebugPrintf("\n");
ds@1952:   if( p->pSrc ){
ds@1952:     char *zPrefix;
ds@1952:     int i;
ds@1952:     zPrefix = "FROM";
ds@1952:     for(i=0; i<p->pSrc->nSrc; i++){
ds@1952:       struct SrcList_item *pItem = &p->pSrc->a[i];
ds@1952:       sqlite3DebugPrintf("%*s ", indent+6, zPrefix);
ds@1952:       zPrefix = "";
ds@1952:       if( pItem->pSelect ){
ds@1952:         sqlite3DebugPrintf("(\n");
ds@1952:         sqlite3PrintSelect(pItem->pSelect, indent+10);
ds@1952:         sqlite3DebugPrintf("%*s)", indent+8, "");
ds@1952:       }else if( pItem->zName ){
ds@1952:         sqlite3DebugPrintf("%s", pItem->zName);
ds@1952:       }
ds@1952:       if( pItem->pTab ){
ds@1952:         sqlite3DebugPrintf("(table: %s)", pItem->pTab->zName);
ds@1952:       }
ds@1952:       if( pItem->zAlias ){
ds@1952:         sqlite3DebugPrintf(" AS %s", pItem->zAlias);
ds@1952:       }
ds@1952:       if( i<p->pSrc->nSrc-1 ){
ds@1952:         sqlite3DebugPrintf(",");
ds@1952:       }
ds@1952:       sqlite3DebugPrintf("\n");
ds@1952:     }
ds@1952:   }
ds@1952:   if( p->pWhere ){
ds@1952:     sqlite3DebugPrintf("%*s WHERE ", indent, "");
ds@1952:     sqlite3PrintExpr(p->pWhere);
ds@1952:     sqlite3DebugPrintf("\n");
ds@1952:   }
ds@1952:   if( p->pGroupBy ){
ds@1952:     sqlite3DebugPrintf("%*s GROUP BY ", indent, "");
ds@1952:     sqlite3PrintExprList(p->pGroupBy);
ds@1952:     sqlite3DebugPrintf("\n");
ds@1952:   }
ds@1952:   if( p->pHaving ){
ds@1952:     sqlite3DebugPrintf("%*s HAVING ", indent, "");
ds@1952:     sqlite3PrintExpr(p->pHaving);
ds@1952:     sqlite3DebugPrintf("\n");
ds@1952:   }
ds@1952:   if( p->pOrderBy ){
ds@1952:     sqlite3DebugPrintf("%*s ORDER BY ", indent, "");
ds@1952:     sqlite3PrintExprList(p->pOrderBy);
ds@1952:     sqlite3DebugPrintf("\n");
ds@1952:   }
ds@1952: }
ds@1952: /* End of the structure debug printing code
ds@1952: *****************************************************************************/
ds@1952: #endif /* defined(SQLITE_TEST) || defined(SQLITE_DEBUG) */