1
2 #pragma ident "%Z%%M% %I% %E% SMI"
3
4 /*
5 ** 2001 September 15
6 **
7 ** The author disclaims copyright to this source code. In place of
8 ** a legal notice, here is a blessing:
9 **
10 ** May you do good and not evil.
11 ** May you find forgiveness for yourself and forgive others.
12 ** May you share freely, never taking more than you give.
13 **
14 *************************************************************************
15 ** This file contains C code routines that are called by the parser
16 ** to handle UPDATE statements.
17 **
18 ** $Id: update.c,v 1.70.2.1 2004/04/29 16:16:29 drh Exp $
19 */
20 #include "sqliteInt.h"
21
22 /*
23 ** Process an UPDATE statement.
24 **
25 ** UPDATE OR IGNORE table_wxyz SET a=b, c=d WHERE e<5 AND f NOT NULL;
26 ** \_______/ \________/ \______/ \________________/
27 * onError pTabList pChanges pWhere
28 */
sqliteUpdate(Parse * pParse,SrcList * pTabList,ExprList * pChanges,Expr * pWhere,int onError)29 void sqliteUpdate(
30 Parse *pParse, /* The parser context */
31 SrcList *pTabList, /* The table in which we should change things */
32 ExprList *pChanges, /* Things to be changed */
33 Expr *pWhere, /* The WHERE clause. May be null */
34 int onError /* How to handle constraint errors */
35 ){
36 int i, j; /* Loop counters */
37 Table *pTab; /* The table to be updated */
38 int loopStart; /* VDBE instruction address of the start of the loop */
39 int jumpInst; /* Addr of VDBE instruction to jump out of loop */
40 WhereInfo *pWInfo; /* Information about the WHERE clause */
41 Vdbe *v; /* The virtual database engine */
42 Index *pIdx; /* For looping over indices */
43 int nIdx; /* Number of indices that need updating */
44 int nIdxTotal; /* Total number of indices */
45 int iCur; /* VDBE Cursor number of pTab */
46 sqlite *db; /* The database structure */
47 Index **apIdx = 0; /* An array of indices that need updating too */
48 char *aIdxUsed = 0; /* aIdxUsed[i]==1 if the i-th index is used */
49 int *aXRef = 0; /* aXRef[i] is the index in pChanges->a[] of the
50 ** an expression for the i-th column of the table.
51 ** aXRef[i]==-1 if the i-th column is not changed. */
52 int chngRecno; /* True if the record number is being changed */
53 Expr *pRecnoExpr; /* Expression defining the new record number */
54 int openAll; /* True if all indices need to be opened */
55 int isView; /* Trying to update a view */
56 int iStackDepth; /* Index of memory cell holding stack depth */
57 AuthContext sContext; /* The authorization context */
58
59 int before_triggers; /* True if there are any BEFORE triggers */
60 int after_triggers; /* True if there are any AFTER triggers */
61 int row_triggers_exist = 0; /* True if any row triggers exist */
62
63 int newIdx = -1; /* index of trigger "new" temp table */
64 int oldIdx = -1; /* index of trigger "old" temp table */
65
66 sContext.pParse = 0;
67 if( pParse->nErr || sqlite_malloc_failed ) goto update_cleanup;
68 db = pParse->db;
69 assert( pTabList->nSrc==1 );
70 iStackDepth = pParse->nMem++;
71
72 /* Locate the table which we want to update.
73 */
74 pTab = sqliteSrcListLookup(pParse, pTabList);
75 if( pTab==0 ) goto update_cleanup;
76 before_triggers = sqliteTriggersExist(pParse, pTab->pTrigger,
77 TK_UPDATE, TK_BEFORE, TK_ROW, pChanges);
78 after_triggers = sqliteTriggersExist(pParse, pTab->pTrigger,
79 TK_UPDATE, TK_AFTER, TK_ROW, pChanges);
80 row_triggers_exist = before_triggers || after_triggers;
81 isView = pTab->pSelect!=0;
82 if( sqliteIsReadOnly(pParse, pTab, before_triggers) ){
83 goto update_cleanup;
84 }
85 if( isView ){
86 if( sqliteViewGetColumnNames(pParse, pTab) ){
87 goto update_cleanup;
88 }
89 }
90 aXRef = sqliteMalloc( sizeof(int) * pTab->nCol );
91 if( aXRef==0 ) goto update_cleanup;
92 for(i=0; i<pTab->nCol; i++) aXRef[i] = -1;
93
94 /* If there are FOR EACH ROW triggers, allocate cursors for the
95 ** special OLD and NEW tables
96 */
97 if( row_triggers_exist ){
98 newIdx = pParse->nTab++;
99 oldIdx = pParse->nTab++;
100 }
101
102 /* Allocate a cursors for the main database table and for all indices.
103 ** The index cursors might not be used, but if they are used they
104 ** need to occur right after the database cursor. So go ahead and
105 ** allocate enough space, just in case.
106 */
107 pTabList->a[0].iCursor = iCur = pParse->nTab++;
108 for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
109 pParse->nTab++;
110 }
111
112 /* Resolve the column names in all the expressions of the
113 ** of the UPDATE statement. Also find the column index
114 ** for each column to be updated in the pChanges array. For each
115 ** column to be updated, make sure we have authorization to change
116 ** that column.
117 */
118 chngRecno = 0;
119 for(i=0; i<pChanges->nExpr; i++){
120 if( sqliteExprResolveIds(pParse, pTabList, 0, pChanges->a[i].pExpr) ){
121 goto update_cleanup;
122 }
123 if( sqliteExprCheck(pParse, pChanges->a[i].pExpr, 0, 0) ){
124 goto update_cleanup;
125 }
126 for(j=0; j<pTab->nCol; j++){
127 if( sqliteStrICmp(pTab->aCol[j].zName, pChanges->a[i].zName)==0 ){
128 if( j==pTab->iPKey ){
129 chngRecno = 1;
130 pRecnoExpr = pChanges->a[i].pExpr;
131 }
132 aXRef[j] = i;
133 break;
134 }
135 }
136 if( j>=pTab->nCol ){
137 if( sqliteIsRowid(pChanges->a[i].zName) ){
138 chngRecno = 1;
139 pRecnoExpr = pChanges->a[i].pExpr;
140 }else{
141 sqliteErrorMsg(pParse, "no such column: %s", pChanges->a[i].zName);
142 goto update_cleanup;
143 }
144 }
145 #ifndef SQLITE_OMIT_AUTHORIZATION
146 {
147 int rc;
148 rc = sqliteAuthCheck(pParse, SQLITE_UPDATE, pTab->zName,
149 pTab->aCol[j].zName, db->aDb[pTab->iDb].zName);
150 if( rc==SQLITE_DENY ){
151 goto update_cleanup;
152 }else if( rc==SQLITE_IGNORE ){
153 aXRef[j] = -1;
154 }
155 }
156 #endif
157 }
158
159 /* Allocate memory for the array apIdx[] and fill it with pointers to every
160 ** index that needs to be updated. Indices only need updating if their
161 ** key includes one of the columns named in pChanges or if the record
162 ** number of the original table entry is changing.
163 */
164 for(nIdx=nIdxTotal=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, nIdxTotal++){
165 if( chngRecno ){
166 i = 0;
167 }else {
168 for(i=0; i<pIdx->nColumn; i++){
169 if( aXRef[pIdx->aiColumn[i]]>=0 ) break;
170 }
171 }
172 if( i<pIdx->nColumn ) nIdx++;
173 }
174 if( nIdxTotal>0 ){
175 apIdx = sqliteMalloc( sizeof(Index*) * nIdx + nIdxTotal );
176 if( apIdx==0 ) goto update_cleanup;
177 aIdxUsed = (char*)&apIdx[nIdx];
178 }
179 for(nIdx=j=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, j++){
180 if( chngRecno ){
181 i = 0;
182 }else{
183 for(i=0; i<pIdx->nColumn; i++){
184 if( aXRef[pIdx->aiColumn[i]]>=0 ) break;
185 }
186 }
187 if( i<pIdx->nColumn ){
188 apIdx[nIdx++] = pIdx;
189 aIdxUsed[j] = 1;
190 }else{
191 aIdxUsed[j] = 0;
192 }
193 }
194
195 /* Resolve the column names in all the expressions in the
196 ** WHERE clause.
197 */
198 if( pWhere ){
199 if( sqliteExprResolveIds(pParse, pTabList, 0, pWhere) ){
200 goto update_cleanup;
201 }
202 if( sqliteExprCheck(pParse, pWhere, 0, 0) ){
203 goto update_cleanup;
204 }
205 }
206
207 /* Start the view context
208 */
209 if( isView ){
210 sqliteAuthContextPush(pParse, &sContext, pTab->zName);
211 }
212
213 /* Begin generating code.
214 */
215 v = sqliteGetVdbe(pParse);
216 if( v==0 ) goto update_cleanup;
217 sqliteBeginWriteOperation(pParse, 1, pTab->iDb);
218
219 /* If we are trying to update a view, construct that view into
220 ** a temporary table.
221 */
222 if( isView ){
223 Select *pView;
224 pView = sqliteSelectDup(pTab->pSelect);
225 sqliteSelect(pParse, pView, SRT_TempTable, iCur, 0, 0, 0);
226 sqliteSelectDelete(pView);
227 }
228
229 /* Begin the database scan
230 */
231 pWInfo = sqliteWhereBegin(pParse, pTabList, pWhere, 1, 0);
232 if( pWInfo==0 ) goto update_cleanup;
233
234 /* Remember the index of every item to be updated.
235 */
236 sqliteVdbeAddOp(v, OP_ListWrite, 0, 0);
237
238 /* End the database scan loop.
239 */
240 sqliteWhereEnd(pWInfo);
241
242 /* Initialize the count of updated rows
243 */
244 if( db->flags & SQLITE_CountRows && !pParse->trigStack ){
245 sqliteVdbeAddOp(v, OP_Integer, 0, 0);
246 }
247
248 if( row_triggers_exist ){
249 /* Create pseudo-tables for NEW and OLD
250 */
251 sqliteVdbeAddOp(v, OP_OpenPseudo, oldIdx, 0);
252 sqliteVdbeAddOp(v, OP_OpenPseudo, newIdx, 0);
253
254 /* The top of the update loop for when there are triggers.
255 */
256 sqliteVdbeAddOp(v, OP_ListRewind, 0, 0);
257 sqliteVdbeAddOp(v, OP_StackDepth, 0, 0);
258 sqliteVdbeAddOp(v, OP_MemStore, iStackDepth, 1);
259 loopStart = sqliteVdbeAddOp(v, OP_MemLoad, iStackDepth, 0);
260 sqliteVdbeAddOp(v, OP_StackReset, 0, 0);
261 jumpInst = sqliteVdbeAddOp(v, OP_ListRead, 0, 0);
262 sqliteVdbeAddOp(v, OP_Dup, 0, 0);
263
264 /* Open a cursor and make it point to the record that is
265 ** being updated.
266 */
267 sqliteVdbeAddOp(v, OP_Dup, 0, 0);
268 if( !isView ){
269 sqliteVdbeAddOp(v, OP_Integer, pTab->iDb, 0);
270 sqliteVdbeAddOp(v, OP_OpenRead, iCur, pTab->tnum);
271 }
272 sqliteVdbeAddOp(v, OP_MoveTo, iCur, 0);
273
274 /* Generate the OLD table
275 */
276 sqliteVdbeAddOp(v, OP_Recno, iCur, 0);
277 sqliteVdbeAddOp(v, OP_RowData, iCur, 0);
278 sqliteVdbeAddOp(v, OP_PutIntKey, oldIdx, 0);
279
280 /* Generate the NEW table
281 */
282 if( chngRecno ){
283 sqliteExprCode(pParse, pRecnoExpr);
284 }else{
285 sqliteVdbeAddOp(v, OP_Recno, iCur, 0);
286 }
287 for(i=0; i<pTab->nCol; i++){
288 if( i==pTab->iPKey ){
289 sqliteVdbeAddOp(v, OP_String, 0, 0);
290 continue;
291 }
292 j = aXRef[i];
293 if( j<0 ){
294 sqliteVdbeAddOp(v, OP_Column, iCur, i);
295 }else{
296 sqliteExprCode(pParse, pChanges->a[j].pExpr);
297 }
298 }
299 sqliteVdbeAddOp(v, OP_MakeRecord, pTab->nCol, 0);
300 sqliteVdbeAddOp(v, OP_PutIntKey, newIdx, 0);
301 if( !isView ){
302 sqliteVdbeAddOp(v, OP_Close, iCur, 0);
303 }
304
305 /* Fire the BEFORE and INSTEAD OF triggers
306 */
307 if( sqliteCodeRowTrigger(pParse, TK_UPDATE, pChanges, TK_BEFORE, pTab,
308 newIdx, oldIdx, onError, loopStart) ){
309 goto update_cleanup;
310 }
311 }
312
313 if( !isView ){
314 /*
315 ** Open every index that needs updating. Note that if any
316 ** index could potentially invoke a REPLACE conflict resolution
317 ** action, then we need to open all indices because we might need
318 ** to be deleting some records.
319 */
320 sqliteVdbeAddOp(v, OP_Integer, pTab->iDb, 0);
321 sqliteVdbeAddOp(v, OP_OpenWrite, iCur, pTab->tnum);
322 if( onError==OE_Replace ){
323 openAll = 1;
324 }else{
325 openAll = 0;
326 for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
327 if( pIdx->onError==OE_Replace ){
328 openAll = 1;
329 break;
330 }
331 }
332 }
333 for(i=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){
334 if( openAll || aIdxUsed[i] ){
335 sqliteVdbeAddOp(v, OP_Integer, pIdx->iDb, 0);
336 sqliteVdbeAddOp(v, OP_OpenWrite, iCur+i+1, pIdx->tnum);
337 assert( pParse->nTab>iCur+i+1 );
338 }
339 }
340
341 /* Loop over every record that needs updating. We have to load
342 ** the old data for each record to be updated because some columns
343 ** might not change and we will need to copy the old value.
344 ** Also, the old data is needed to delete the old index entires.
345 ** So make the cursor point at the old record.
346 */
347 if( !row_triggers_exist ){
348 sqliteVdbeAddOp(v, OP_ListRewind, 0, 0);
349 jumpInst = loopStart = sqliteVdbeAddOp(v, OP_ListRead, 0, 0);
350 sqliteVdbeAddOp(v, OP_Dup, 0, 0);
351 }
352 sqliteVdbeAddOp(v, OP_NotExists, iCur, loopStart);
353
354 /* If the record number will change, push the record number as it
355 ** will be after the update. (The old record number is currently
356 ** on top of the stack.)
357 */
358 if( chngRecno ){
359 sqliteExprCode(pParse, pRecnoExpr);
360 sqliteVdbeAddOp(v, OP_MustBeInt, 0, 0);
361 }
362
363 /* Compute new data for this record.
364 */
365 for(i=0; i<pTab->nCol; i++){
366 if( i==pTab->iPKey ){
367 sqliteVdbeAddOp(v, OP_String, 0, 0);
368 continue;
369 }
370 j = aXRef[i];
371 if( j<0 ){
372 sqliteVdbeAddOp(v, OP_Column, iCur, i);
373 }else{
374 sqliteExprCode(pParse, pChanges->a[j].pExpr);
375 }
376 }
377
378 /* Do constraint checks
379 */
380 sqliteGenerateConstraintChecks(pParse, pTab, iCur, aIdxUsed, chngRecno, 1,
381 onError, loopStart);
382
383 /* Delete the old indices for the current record.
384 */
385 sqliteGenerateRowIndexDelete(db, v, pTab, iCur, aIdxUsed);
386
387 /* If changing the record number, delete the old record.
388 */
389 if( chngRecno ){
390 sqliteVdbeAddOp(v, OP_Delete, iCur, 0);
391 }
392
393 /* Create the new index entries and the new record.
394 */
395 sqliteCompleteInsertion(pParse, pTab, iCur, aIdxUsed, chngRecno, 1, -1);
396 }
397
398 /* Increment the row counter
399 */
400 if( db->flags & SQLITE_CountRows && !pParse->trigStack){
401 sqliteVdbeAddOp(v, OP_AddImm, 1, 0);
402 }
403
404 /* If there are triggers, close all the cursors after each iteration
405 ** through the loop. The fire the after triggers.
406 */
407 if( row_triggers_exist ){
408 if( !isView ){
409 for(i=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){
410 if( openAll || aIdxUsed[i] )
411 sqliteVdbeAddOp(v, OP_Close, iCur+i+1, 0);
412 }
413 sqliteVdbeAddOp(v, OP_Close, iCur, 0);
414 pParse->nTab = iCur;
415 }
416 if( sqliteCodeRowTrigger(pParse, TK_UPDATE, pChanges, TK_AFTER, pTab,
417 newIdx, oldIdx, onError, loopStart) ){
418 goto update_cleanup;
419 }
420 }
421
422 /* Repeat the above with the next record to be updated, until
423 ** all record selected by the WHERE clause have been updated.
424 */
425 sqliteVdbeAddOp(v, OP_Goto, 0, loopStart);
426 sqliteVdbeChangeP2(v, jumpInst, sqliteVdbeCurrentAddr(v));
427 sqliteVdbeAddOp(v, OP_ListReset, 0, 0);
428
429 /* Close all tables if there were no FOR EACH ROW triggers */
430 if( !row_triggers_exist ){
431 for(i=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){
432 if( openAll || aIdxUsed[i] ){
433 sqliteVdbeAddOp(v, OP_Close, iCur+i+1, 0);
434 }
435 }
436 sqliteVdbeAddOp(v, OP_Close, iCur, 0);
437 pParse->nTab = iCur;
438 }else{
439 sqliteVdbeAddOp(v, OP_Close, newIdx, 0);
440 sqliteVdbeAddOp(v, OP_Close, oldIdx, 0);
441 }
442
443 sqliteVdbeAddOp(v, OP_SetCounts, 0, 0);
444 sqliteEndWriteOperation(pParse);
445
446 /*
447 ** Return the number of rows that were changed.
448 */
449 if( db->flags & SQLITE_CountRows && !pParse->trigStack ){
450 sqliteVdbeOp3(v, OP_ColumnName, 0, 1, "rows updated", P3_STATIC);
451 sqliteVdbeAddOp(v, OP_Callback, 1, 0);
452 }
453
454 update_cleanup:
455 sqliteAuthContextPop(&sContext);
456 sqliteFree(apIdx);
457 sqliteFree(aXRef);
458 sqliteSrcListDelete(pTabList);
459 sqliteExprListDelete(pChanges);
460 sqliteExprDelete(pWhere);
461 return;
462 }
463