4 ** The author disclaims copyright to this source code. In place of
5 ** a legal notice, here is a blessing:
7 ** May you do good and not evil.
8 ** May you find forgiveness for yourself and forgive others.
9 ** May you share freely, never taking more than you give.
11 *************************************************************************
12 ** This file contains C code routines that are called by the parser
13 ** to handle UPDATE statements.
17 #include "sqliteInt.h"
19 #ifndef SQLITE_OMIT_VIRTUALTABLE
20 /* Forward declaration */
21 static void updateVirtualTable(
22 Parse *pParse, /* The parsing context */
23 SrcList *pSrc, /* The virtual table to be modified */
24 Table *pTab, /* The virtual table */
25 ExprList *pChanges, /* The columns to change in the UPDATE statement */
26 Expr *pRowidExpr, /* Expression used to recompute the rowid */
27 int *aXRef, /* Mapping from columns of pTab to entries in pChanges */
28 Expr *pWhere /* WHERE clause of the UPDATE statement */
30 #endif /* SQLITE_OMIT_VIRTUALTABLE */
33 ** The most recently coded instruction was an OP_Column to retrieve the
34 ** i-th column of table pTab. This routine sets the P3 parameter of the
35 ** OP_Column to the default value, if any.
37 ** The default value of a column is specified by a DEFAULT clause in the
38 ** column definition. This was either supplied by the user when the table
39 ** was created, or added later to the table definition by an ALTER TABLE
40 ** command. If the latter, then the row-records in the table btree on disk
41 ** may not contain a value for the column and the default value, taken
42 ** from the P3 parameter of the OP_Column instruction, is returned instead.
43 ** If the former, then all row-records are guaranteed to include a value
44 ** for the column and the P3 value is not required.
46 ** Column definitions created by an ALTER TABLE command may only have
47 ** literal default values specified: a number, null or a string. (If a more
48 ** complicated default expression value was provided, it is evaluated
49 ** when the ALTER TABLE is executed and one of the literal values written
50 ** into the sqlite_master table.)
52 ** Therefore, the P3 parameter is only required if the default value for
53 ** the column is a literal number, string or null. The sqlite3ValueFromExpr()
54 ** function is capable of transforming these types of expressions into
55 ** sqlite3_value objects.
57 void sqlite3ColumnDefault(Vdbe *v, Table *pTab, int i){
58 if( pTab && !pTab->pSelect ){
59 sqlite3_value *pValue;
60 u8 enc = ENC(sqlite3VdbeDb(v));
61 Column *pCol = &pTab->aCol[i];
62 assert( i<pTab->nCol );
63 sqlite3ValueFromExpr(sqlite3VdbeDb(v), pCol->pDflt, enc, pCol->affinity, &pValue);
65 sqlite3VdbeChangeP3(v, -1, (const char *)pValue, P3_MEM);
67 VdbeComment((v, "# %s.%s", pTab->zName, pCol->zName));
73 ** Process an UPDATE statement.
75 ** UPDATE OR IGNORE table_wxyz SET a=b, c=d WHERE e<5 AND f NOT NULL;
76 ** \_______/ \________/ \______/ \________________/
77 * onError pTabList pChanges pWhere
80 Parse *pParse, /* The parser context */
81 SrcList *pTabList, /* The table in which we should change things */
82 ExprList *pChanges, /* Things to be changed */
83 Expr *pWhere, /* The WHERE clause. May be null */
84 int onError /* How to handle constraint errors */
86 int i, j; /* Loop counters */
87 Table *pTab; /* The table to be updated */
88 int addr = 0; /* VDBE instruction address of the start of the loop */
89 WhereInfo *pWInfo; /* Information about the WHERE clause */
90 Vdbe *v; /* The virtual database engine */
91 Index *pIdx; /* For looping over indices */
92 int nIdx; /* Number of indices that need updating */
93 int nIdxTotal; /* Total number of indices */
94 int iCur; /* VDBE Cursor number of pTab */
95 sqlite3 *db; /* The database structure */
96 Index **apIdx = 0; /* An array of indices that need updating too */
97 char *aIdxUsed = 0; /* aIdxUsed[i]==1 if the i-th index is used */
98 int *aXRef = 0; /* aXRef[i] is the index in pChanges->a[] of the
99 ** an expression for the i-th column of the table.
100 ** aXRef[i]==-1 if the i-th column is not changed. */
101 int chngRowid; /* True if the record number is being changed */
102 Expr *pRowidExpr = 0; /* Expression defining the new record number */
103 int openAll = 0; /* True if all indices need to be opened */
104 AuthContext sContext; /* The authorization context */
105 NameContext sNC; /* The name-context to resolve expressions in */
106 int iDb; /* Database containing the table being updated */
107 int memCnt = 0; /* Memory cell used for counting rows changed */
109 #ifndef SQLITE_OMIT_TRIGGER
110 int isView; /* Trying to update a view */
111 int triggers_exist = 0; /* True if any row triggers exist */
114 int newIdx = -1; /* index of trigger "new" temp table */
115 int oldIdx = -1; /* index of trigger "old" temp table */
119 if( pParse->nErr || db->mallocFailed ){
122 assert( pTabList->nSrc==1 );
124 /* Locate the table which we want to update.
126 pTab = sqlite3SrcListLookup(pParse, pTabList);
127 if( pTab==0 ) goto update_cleanup;
128 iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);
130 /* Figure out if we have any triggers and if the table being
133 #ifndef SQLITE_OMIT_TRIGGER
134 triggers_exist = sqlite3TriggersExist(pParse, pTab, TK_UPDATE, pChanges);
135 isView = pTab->pSelect!=0;
137 # define triggers_exist 0
140 #ifdef SQLITE_OMIT_VIEW
145 if( sqlite3IsReadOnly(pParse, pTab, triggers_exist) ){
148 if( sqlite3ViewGetColumnNames(pParse, pTab) ){
151 aXRef = sqlite3DbMallocRaw(db, sizeof(int) * pTab->nCol );
152 if( aXRef==0 ) goto update_cleanup;
153 for(i=0; i<pTab->nCol; i++) aXRef[i] = -1;
155 /* If there are FOR EACH ROW triggers, allocate cursors for the
156 ** special OLD and NEW tables
158 if( triggers_exist ){
159 newIdx = pParse->nTab++;
160 oldIdx = pParse->nTab++;
163 /* Allocate a cursors for the main database table and for all indices.
164 ** The index cursors might not be used, but if they are used they
165 ** need to occur right after the database cursor. So go ahead and
166 ** allocate enough space, just in case.
168 pTabList->a[0].iCursor = iCur = pParse->nTab++;
169 for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
173 /* Initialize the name-context */
174 memset(&sNC, 0, sizeof(sNC));
176 sNC.pSrcList = pTabList;
178 /* Resolve the column names in all the expressions of the
179 ** of the UPDATE statement. Also find the column index
180 ** for each column to be updated in the pChanges array. For each
181 ** column to be updated, make sure we have authorization to change
185 for(i=0; i<pChanges->nExpr; i++){
186 if( sqlite3ExprResolveNames(&sNC, pChanges->a[i].pExpr) ){
189 for(j=0; j<pTab->nCol; j++){
190 if( sqlite3StrICmp(pTab->aCol[j].zName, pChanges->a[i].zName)==0 ){
191 if( j==pTab->iPKey ){
193 pRowidExpr = pChanges->a[i].pExpr;
200 if( sqlite3IsRowid(pChanges->a[i].zName) ){
202 pRowidExpr = pChanges->a[i].pExpr;
204 sqlite3ErrorMsg(pParse, "no such column: %s", pChanges->a[i].zName);
208 #ifndef SQLITE_OMIT_AUTHORIZATION
211 rc = sqlite3AuthCheck(pParse, SQLITE_UPDATE, pTab->zName,
212 pTab->aCol[j].zName, db->aDb[iDb].zName);
213 if( rc==SQLITE_DENY ){
215 }else if( rc==SQLITE_IGNORE ){
222 /* Allocate memory for the array apIdx[] and fill it with pointers to every
223 ** index that needs to be updated. Indices only need updating if their
224 ** key includes one of the columns named in pChanges or if the record
225 ** number of the original table entry is changing.
227 for(nIdx=nIdxTotal=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, nIdxTotal++){
231 for(i=0; i<pIdx->nColumn; i++){
232 if( aXRef[pIdx->aiColumn[i]]>=0 ) break;
235 if( i<pIdx->nColumn ) nIdx++;
238 apIdx = sqlite3DbMallocRaw(db, sizeof(Index*) * nIdx + nIdxTotal );
239 if( apIdx==0 ) goto update_cleanup;
240 aIdxUsed = (char*)&apIdx[nIdx];
242 for(nIdx=j=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, j++){
246 for(i=0; i<pIdx->nColumn; i++){
247 if( aXRef[pIdx->aiColumn[i]]>=0 ) break;
250 if( i<pIdx->nColumn ){
251 apIdx[nIdx++] = pIdx;
258 /* Begin generating code.
260 v = sqlite3GetVdbe(pParse);
261 if( v==0 ) goto update_cleanup;
262 if( pParse->nested==0 ) sqlite3VdbeCountChanges(v);
263 sqlite3BeginWriteOperation(pParse, 1, iDb);
265 #ifndef SQLITE_OMIT_VIRTUALTABLE
266 /* Virtual tables must be handled separately */
267 if( IsVirtual(pTab) ){
268 updateVirtualTable(pParse, pTabList, pTab, pChanges, pRowidExpr, aXRef,
276 /* Resolve the column names in all the expressions in the
279 if( sqlite3ExprResolveNames(&sNC, pWhere) ){
283 /* Start the view context
286 sqlite3AuthContextPush(pParse, &sContext, pTab->zName);
289 /* If we are trying to update a view, realize that view into
290 ** a ephemeral table.
294 pView = sqlite3SelectDup(db, pTab->pSelect);
295 sqlite3Select(pParse, pView, SRT_EphemTab, iCur, 0, 0, 0, 0);
296 sqlite3SelectDelete(pView);
299 /* Begin the database scan
301 pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, 0);
302 if( pWInfo==0 ) goto update_cleanup;
304 /* Remember the rowid of every item to be updated.
306 sqlite3VdbeAddOp(v, IsVirtual(pTab) ? OP_VRowid : OP_Rowid, iCur, 0);
307 sqlite3VdbeAddOp(v, OP_FifoWrite, 0, 0);
309 /* End the database scan loop.
311 sqlite3WhereEnd(pWInfo);
313 /* Initialize the count of updated rows
315 if( db->flags & SQLITE_CountRows && !pParse->trigStack ){
316 memCnt = pParse->nMem++;
317 sqlite3VdbeAddOp(v, OP_MemInt, 0, memCnt);
320 if( triggers_exist ){
321 /* Create pseudo-tables for NEW and OLD
323 sqlite3VdbeAddOp(v, OP_OpenPseudo, oldIdx, 0);
324 sqlite3VdbeAddOp(v, OP_SetNumColumns, oldIdx, pTab->nCol);
325 sqlite3VdbeAddOp(v, OP_OpenPseudo, newIdx, 0);
326 sqlite3VdbeAddOp(v, OP_SetNumColumns, newIdx, pTab->nCol);
328 /* The top of the update loop for when there are triggers.
330 addr = sqlite3VdbeAddOp(v, OP_FifoRead, 0, 0);
333 sqlite3VdbeAddOp(v, OP_Dup, 0, 0);
334 sqlite3VdbeAddOp(v, OP_Dup, 0, 0);
335 /* Open a cursor and make it point to the record that is
338 sqlite3OpenTable(pParse, iCur, iDb, pTab, OP_OpenRead);
340 sqlite3VdbeAddOp(v, OP_MoveGe, iCur, 0);
342 /* Generate the OLD table
344 sqlite3VdbeAddOp(v, OP_Rowid, iCur, 0);
345 sqlite3VdbeAddOp(v, OP_RowData, iCur, 0);
346 sqlite3VdbeAddOp(v, OP_Insert, oldIdx, 0);
348 /* Generate the NEW table
351 sqlite3ExprCodeAndCache(pParse, pRowidExpr);
353 sqlite3VdbeAddOp(v, OP_Rowid, iCur, 0);
355 for(i=0; i<pTab->nCol; i++){
356 if( i==pTab->iPKey ){
357 sqlite3VdbeAddOp(v, OP_Null, 0, 0);
362 sqlite3VdbeAddOp(v, OP_Column, iCur, i);
363 sqlite3ColumnDefault(v, pTab, i);
365 sqlite3ExprCodeAndCache(pParse, pChanges->a[j].pExpr);
368 sqlite3VdbeAddOp(v, OP_MakeRecord, pTab->nCol, 0);
370 sqlite3TableAffinityStr(v, pTab);
372 if( pParse->nErr ) goto update_cleanup;
373 sqlite3VdbeAddOp(v, OP_Insert, newIdx, 0);
375 sqlite3VdbeAddOp(v, OP_Close, iCur, 0);
378 /* Fire the BEFORE and INSTEAD OF triggers
380 if( sqlite3CodeRowTrigger(pParse, TK_UPDATE, pChanges, TRIGGER_BEFORE, pTab,
381 newIdx, oldIdx, onError, addr) ){
386 if( !isView && !IsVirtual(pTab) ){
388 ** Open every index that needs updating. Note that if any
389 ** index could potentially invoke a REPLACE conflict resolution
390 ** action, then we need to open all indices because we might need
391 ** to be deleting some records.
393 sqlite3OpenTable(pParse, iCur, iDb, pTab, OP_OpenWrite);
394 if( onError==OE_Replace ){
398 for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
399 if( pIdx->onError==OE_Replace ){
405 for(i=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){
406 if( openAll || aIdxUsed[i] ){
407 KeyInfo *pKey = sqlite3IndexKeyinfo(pParse, pIdx);
408 sqlite3VdbeAddOp(v, OP_Integer, iDb, 0);
409 sqlite3VdbeOp3(v, OP_OpenWrite, iCur+i+1, pIdx->tnum,
410 (char*)pKey, P3_KEYINFO_HANDOFF);
411 assert( pParse->nTab>iCur+i+1 );
415 /* Loop over every record that needs updating. We have to load
416 ** the old data for each record to be updated because some columns
417 ** might not change and we will need to copy the old value.
418 ** Also, the old data is needed to delete the old index entries.
419 ** So make the cursor point at the old record.
421 if( !triggers_exist ){
422 addr = sqlite3VdbeAddOp(v, OP_FifoRead, 0, 0);
423 sqlite3VdbeAddOp(v, OP_Dup, 0, 0);
425 sqlite3VdbeAddOp(v, OP_NotExists, iCur, addr);
427 /* If the record number will change, push the record number as it
428 ** will be after the update. (The old record number is currently
429 ** on top of the stack.)
432 sqlite3ExprCode(pParse, pRowidExpr);
433 sqlite3VdbeAddOp(v, OP_MustBeInt, 0, 0);
436 /* Compute new data for this record.
438 for(i=0; i<pTab->nCol; i++){
439 if( i==pTab->iPKey ){
440 sqlite3VdbeAddOp(v, OP_Null, 0, 0);
445 sqlite3VdbeAddOp(v, OP_Column, iCur, i);
446 sqlite3ColumnDefault(v, pTab, i);
448 sqlite3ExprCode(pParse, pChanges->a[j].pExpr);
452 /* Do constraint checks
454 sqlite3GenerateConstraintChecks(pParse, pTab, iCur, aIdxUsed, chngRowid, 1,
457 /* Delete the old indices for the current record.
459 sqlite3GenerateRowIndexDelete(v, pTab, iCur, aIdxUsed);
461 /* If changing the record number, delete the old record.
464 sqlite3VdbeAddOp(v, OP_Delete, iCur, 0);
467 /* Create the new index entries and the new record.
469 sqlite3CompleteInsertion(pParse, pTab, iCur, aIdxUsed, chngRowid, 1, -1, 0);
472 /* Increment the row counter
474 if( db->flags & SQLITE_CountRows && !pParse->trigStack){
475 sqlite3VdbeAddOp(v, OP_MemIncr, 1, memCnt);
478 /* If there are triggers, close all the cursors after each iteration
479 ** through the loop. The fire the after triggers.
481 if( triggers_exist ){
483 for(i=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){
484 if( openAll || aIdxUsed[i] )
485 sqlite3VdbeAddOp(v, OP_Close, iCur+i+1, 0);
487 sqlite3VdbeAddOp(v, OP_Close, iCur, 0);
489 if( sqlite3CodeRowTrigger(pParse, TK_UPDATE, pChanges, TRIGGER_AFTER, pTab,
490 newIdx, oldIdx, onError, addr) ){
495 /* Repeat the above with the next record to be updated, until
496 ** all record selected by the WHERE clause have been updated.
498 sqlite3VdbeAddOp(v, OP_Goto, 0, addr);
499 sqlite3VdbeJumpHere(v, addr);
501 /* Close all tables if there were no FOR EACH ROW triggers */
502 if( !triggers_exist ){
503 for(i=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){
504 if( openAll || aIdxUsed[i] ){
505 sqlite3VdbeAddOp(v, OP_Close, iCur+i+1, 0);
508 sqlite3VdbeAddOp(v, OP_Close, iCur, 0);
510 sqlite3VdbeAddOp(v, OP_Close, newIdx, 0);
511 sqlite3VdbeAddOp(v, OP_Close, oldIdx, 0);
515 ** Return the number of rows that were changed. If this routine is
516 ** generating code because of a call to sqlite3NestedParse(), do not
517 ** invoke the callback function.
519 if( db->flags & SQLITE_CountRows && !pParse->trigStack && pParse->nested==0 ){
520 sqlite3VdbeAddOp(v, OP_MemLoad, memCnt, 0);
521 sqlite3VdbeAddOp(v, OP_Callback, 1, 0);
522 sqlite3VdbeSetNumCols(v, 1);
523 sqlite3VdbeSetColName(v, 0, COLNAME_NAME, "rows updated", P3_STATIC);
527 sqlite3AuthContextPop(&sContext);
530 sqlite3SrcListDelete(pTabList);
531 sqlite3ExprListDelete(pChanges);
532 sqlite3ExprDelete(pWhere);
536 #ifndef SQLITE_OMIT_VIRTUALTABLE
538 ** Generate code for an UPDATE of a virtual table.
540 ** The strategy is that we create an ephemerial table that contains
541 ** for each row to be changed:
543 ** (A) The original rowid of that row.
544 ** (B) The revised rowid for the row. (note1)
545 ** (C) The content of every column in the row.
547 ** Then we loop over this ephemeral table and for each row in
548 ** the ephermeral table call VUpdate.
550 ** When finished, drop the ephemeral table.
552 ** (note1) Actually, if we know in advance that (A) is always the same
553 ** as (B) we only store (A), then duplicate (A) when pulling
554 ** it out of the ephemeral table before calling VUpdate.
556 static void updateVirtualTable(
557 Parse *pParse, /* The parsing context */
558 SrcList *pSrc, /* The virtual table to be modified */
559 Table *pTab, /* The virtual table */
560 ExprList *pChanges, /* The columns to change in the UPDATE statement */
561 Expr *pRowid, /* Expression used to recompute the rowid */
562 int *aXRef, /* Mapping from columns of pTab to entries in pChanges */
563 Expr *pWhere /* WHERE clause of the UPDATE statement */
565 Vdbe *v = pParse->pVdbe; /* Virtual machine under construction */
566 ExprList *pEList = 0; /* The result set of the SELECT statement */
567 Select *pSelect = 0; /* The SELECT statement */
568 Expr *pExpr; /* Temporary expression */
569 int ephemTab; /* Table holding the result of the SELECT */
570 int i; /* Loop counter */
571 int addr; /* Address of top of loop */
572 sqlite3 *db = pParse->db; /* Database connection */
574 /* Construct the SELECT statement that will find the new values for
577 pEList = sqlite3ExprListAppend(pParse, 0,
578 sqlite3CreateIdExpr(pParse, "_rowid_"), 0);
580 pEList = sqlite3ExprListAppend(pParse, pEList,
581 sqlite3ExprDup(db, pRowid), 0);
583 assert( pTab->iPKey<0 );
584 for(i=0; i<pTab->nCol; i++){
586 pExpr = sqlite3ExprDup(db, pChanges->a[aXRef[i]].pExpr);
588 pExpr = sqlite3CreateIdExpr(pParse, pTab->aCol[i].zName);
590 pEList = sqlite3ExprListAppend(pParse, pEList, pExpr, 0);
592 pSelect = sqlite3SelectNew(pParse, pEList, pSrc, pWhere, 0, 0, 0, 0, 0, 0);
594 /* Create the ephemeral table into which the update results will
598 ephemTab = pParse->nTab++;
599 sqlite3VdbeAddOp(v, OP_OpenEphemeral, ephemTab, pTab->nCol+1+(pRowid!=0));
601 /* fill the ephemeral table
603 sqlite3Select(pParse, pSelect, SRT_Table, ephemTab, 0, 0, 0, 0);
606 ** Generate code to scan the ephemeral table and call VDelete and
609 sqlite3VdbeAddOp(v, OP_Rewind, ephemTab, 0);
610 addr = sqlite3VdbeCurrentAddr(v);
611 sqlite3VdbeAddOp(v, OP_Column, ephemTab, 0);
613 sqlite3VdbeAddOp(v, OP_Column, ephemTab, 1);
615 sqlite3VdbeAddOp(v, OP_Dup, 0, 0);
617 for(i=0; i<pTab->nCol; i++){
618 sqlite3VdbeAddOp(v, OP_Column, ephemTab, i+1+(pRowid!=0));
620 pParse->pVirtualLock = pTab;
621 sqlite3VdbeOp3(v, OP_VUpdate, 0, pTab->nCol+2,
622 (const char*)pTab->pVtab, P3_VTAB);
623 sqlite3VdbeAddOp(v, OP_Next, ephemTab, addr);
624 sqlite3VdbeJumpHere(v, addr-1);
625 sqlite3VdbeAddOp(v, OP_Close, ephemTab, 0);
628 sqlite3SelectDelete(pSelect);
630 #endif /* SQLITE_OMIT_VIRTUALTABLE */