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 */ 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