1 /* 2 ** 2001 September 15 3 ** 4 ** The author disclaims copyright to this source code. In place of 5 ** a legal notice, here is a blessing: 6 ** 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. 10 ** 11 ************************************************************************* 12 ** This file contains C code routines that are called by the parser 13 ** to handle UPDATE statements. 14 ** 15 ** $Id: update.c,v 1.67 2003/06/01 01:10:33 drh Exp $ 16 */ 17 #include "sqliteInt.h" 18 19 /* 20 ** Process an UPDATE statement. 21 ** 22 ** UPDATE OR IGNORE table_wxyz SET a=b, c=d WHERE e<5 AND f NOT NULL; 23 ** \_______/ \________/ \______/ \________________/ 24 * onError pTabList pChanges pWhere 25 */ 26 void sqliteUpdate( 27 Parse *pParse, /* The parser context */ 28 SrcList *pTabList, /* The table in which we should change things */ 29 ExprList *pChanges, /* Things to be changed */ 30 Expr *pWhere, /* The WHERE clause. May be null */ 31 int onError /* How to handle constraint errors */ 32 ){ 33 int i, j; /* Loop counters */ 34 Table *pTab; /* The table to be updated */ 35 int addr; /* VDBE instruction address of the start of the loop */ 36 WhereInfo *pWInfo; /* Information about the WHERE clause */ 37 Vdbe *v; /* The virtual database engine */ 38 Index *pIdx; /* For looping over indices */ 39 int nIdx; /* Number of indices that need updating */ 40 int nIdxTotal; /* Total number of indices */ 41 int iCur; /* VDBE Cursor number of pTab */ 42 sqlite *db; /* The database structure */ 43 Index **apIdx = 0; /* An array of indices that need updating too */ 44 char *aIdxUsed = 0; /* aIdxUsed[i]==1 if the i-th index is used */ 45 int *aXRef = 0; /* aXRef[i] is the index in pChanges->a[] of the 46 ** an expression for the i-th column of the table. 47 ** aXRef[i]==-1 if the i-th column is not changed. */ 48 int chngRecno; /* True if the record number is being changed */ 49 Expr *pRecnoExpr; /* Expression defining the new record number */ 50 int openAll; /* True if all indices need to be opened */ 51 int isView; /* Trying to update a view */ 52 AuthContext sContext; /* The authorization context */ 53 54 int before_triggers; /* True if there are any BEFORE triggers */ 55 int after_triggers; /* True if there are any AFTER triggers */ 56 int row_triggers_exist = 0; /* True if any row triggers exist */ 57 58 int newIdx = -1; /* index of trigger "new" temp table */ 59 int oldIdx = -1; /* index of trigger "old" temp table */ 60 61 sContext.pParse = 0; 62 if( pParse->nErr || sqlite_malloc_failed ) goto update_cleanup; 63 db = pParse->db; 64 assert( pTabList->nSrc==1 ); 65 66 /* Locate the table which we want to update. 67 */ 68 pTab = sqliteSrcListLookup(pParse, pTabList); 69 if( pTab==0 ) goto update_cleanup; 70 before_triggers = sqliteTriggersExist(pParse, pTab->pTrigger, 71 TK_UPDATE, TK_BEFORE, TK_ROW, pChanges); 72 after_triggers = sqliteTriggersExist(pParse, pTab->pTrigger, 73 TK_UPDATE, TK_AFTER, TK_ROW, pChanges); 74 row_triggers_exist = before_triggers || after_triggers; 75 isView = pTab->pSelect!=0; 76 if( sqliteIsReadOnly(pParse, pTab, before_triggers) ){ 77 goto update_cleanup; 78 } 79 if( isView ){ 80 if( sqliteViewGetColumnNames(pParse, pTab) ){ 81 goto update_cleanup; 82 } 83 } 84 aXRef = sqliteMalloc( sizeof(int) * pTab->nCol ); 85 if( aXRef==0 ) goto update_cleanup; 86 for(i=0; i<pTab->nCol; i++) aXRef[i] = -1; 87 88 /* If there are FOR EACH ROW triggers, allocate cursors for the 89 ** special OLD and NEW tables 90 */ 91 if( row_triggers_exist ){ 92 newIdx = pParse->nTab++; 93 oldIdx = pParse->nTab++; 94 } 95 96 /* Allocate a cursors for the main database table and for all indices. 97 ** The index cursors might not be used, but if they are used they 98 ** need to occur right after the database cursor. So go ahead and 99 ** allocate enough space, just in case. 100 */ 101 pTabList->a[0].iCursor = iCur = pParse->nTab++; 102 for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){ 103 pParse->nTab++; 104 } 105 106 /* Resolve the column names in all the expressions of the 107 ** of the UPDATE statement. Also find the column index 108 ** for each column to be updated in the pChanges array. For each 109 ** column to be updated, make sure we have authorization to change 110 ** that column. 111 */ 112 chngRecno = 0; 113 for(i=0; i<pChanges->nExpr; i++){ 114 if( sqliteExprResolveIds(pParse, pTabList, 0, pChanges->a[i].pExpr) ){ 115 goto update_cleanup; 116 } 117 if( sqliteExprCheck(pParse, pChanges->a[i].pExpr, 0, 0) ){ 118 goto update_cleanup; 119 } 120 for(j=0; j<pTab->nCol; j++){ 121 if( sqliteStrICmp(pTab->aCol[j].zName, pChanges->a[i].zName)==0 ){ 122 if( j==pTab->iPKey ){ 123 chngRecno = 1; 124 pRecnoExpr = pChanges->a[i].pExpr; 125 } 126 aXRef[j] = i; 127 break; 128 } 129 } 130 if( j>=pTab->nCol ){ 131 if( sqliteIsRowid(pChanges->a[i].zName) ){ 132 chngRecno = 1; 133 pRecnoExpr = pChanges->a[i].pExpr; 134 }else{ 135 sqliteErrorMsg(pParse, "no such column: %s", pChanges->a[i].zName); 136 goto update_cleanup; 137 } 138 } 139 #ifndef SQLITE_OMIT_AUTHORIZATION 140 { 141 int rc; 142 rc = sqliteAuthCheck(pParse, SQLITE_UPDATE, pTab->zName, 143 pTab->aCol[j].zName, db->aDb[pTab->iDb].zName); 144 if( rc==SQLITE_DENY ){ 145 goto update_cleanup; 146 }else if( rc==SQLITE_IGNORE ){ 147 aXRef[j] = -1; 148 } 149 } 150 #endif 151 } 152 153 /* Allocate memory for the array apIdx[] and fill it with pointers to every 154 ** index that needs to be updated. Indices only need updating if their 155 ** key includes one of the columns named in pChanges or if the record 156 ** number of the original table entry is changing. 157 */ 158 for(nIdx=nIdxTotal=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, nIdxTotal++){ 159 if( chngRecno ){ 160 i = 0; 161 }else { 162 for(i=0; i<pIdx->nColumn; i++){ 163 if( aXRef[pIdx->aiColumn[i]]>=0 ) break; 164 } 165 } 166 if( i<pIdx->nColumn ) nIdx++; 167 } 168 if( nIdxTotal>0 ){ 169 apIdx = sqliteMalloc( sizeof(Index*) * nIdx + nIdxTotal ); 170 if( apIdx==0 ) goto update_cleanup; 171 aIdxUsed = (char*)&apIdx[nIdx]; 172 } 173 for(nIdx=j=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, j++){ 174 if( chngRecno ){ 175 i = 0; 176 }else{ 177 for(i=0; i<pIdx->nColumn; i++){ 178 if( aXRef[pIdx->aiColumn[i]]>=0 ) break; 179 } 180 } 181 if( i<pIdx->nColumn ){ 182 apIdx[nIdx++] = pIdx; 183 aIdxUsed[j] = 1; 184 }else{ 185 aIdxUsed[j] = 0; 186 } 187 } 188 189 /* Resolve the column names in all the expressions in the 190 ** WHERE clause. 191 */ 192 if( pWhere ){ 193 if( sqliteExprResolveIds(pParse, pTabList, 0, pWhere) ){ 194 goto update_cleanup; 195 } 196 if( sqliteExprCheck(pParse, pWhere, 0, 0) ){ 197 goto update_cleanup; 198 } 199 } 200 201 /* Start the view context 202 */ 203 if( isView ){ 204 sqliteAuthContextPush(pParse, &sContext, pTab->zName); 205 } 206 207 /* Begin generating code. 208 */ 209 v = sqliteGetVdbe(pParse); 210 if( v==0 ) goto update_cleanup; 211 sqliteBeginWriteOperation(pParse, 1, pTab->iDb); 212 213 /* If we are trying to update a view, construct that view into 214 ** a temporary table. 215 */ 216 if( isView ){ 217 Select *pView; 218 pView = sqliteSelectDup(pTab->pSelect); 219 sqliteSelect(pParse, pView, SRT_TempTable, iCur, 0, 0, 0); 220 sqliteSelectDelete(pView); 221 } 222 223 /* Begin the database scan 224 */ 225 pWInfo = sqliteWhereBegin(pParse, pTabList, pWhere, 1, 0); 226 if( pWInfo==0 ) goto update_cleanup; 227 228 /* Remember the index of every item to be updated. 229 */ 230 sqliteVdbeAddOp(v, OP_ListWrite, 0, 0); 231 232 /* End the database scan loop. 233 */ 234 sqliteWhereEnd(pWInfo); 235 236 /* Initialize the count of updated rows 237 */ 238 if( db->flags & SQLITE_CountRows && !pParse->trigStack ){ 239 sqliteVdbeAddOp(v, OP_Integer, 0, 0); 240 } 241 242 if( row_triggers_exist ){ 243 /* Create pseudo-tables for NEW and OLD 244 */ 245 sqliteVdbeAddOp(v, OP_OpenPseudo, oldIdx, 0); 246 sqliteVdbeAddOp(v, OP_OpenPseudo, newIdx, 0); 247 248 /* The top of the update loop for when there are triggers. 249 */ 250 sqliteVdbeAddOp(v, OP_ListRewind, 0, 0); 251 addr = sqliteVdbeAddOp(v, OP_ListRead, 0, 0); 252 sqliteVdbeAddOp(v, OP_Dup, 0, 0); 253 254 /* Open a cursor and make it point to the record that is 255 ** being updated. 256 */ 257 sqliteVdbeAddOp(v, OP_Dup, 0, 0); 258 if( !isView ){ 259 sqliteVdbeAddOp(v, OP_Integer, pTab->iDb, 0); 260 sqliteVdbeAddOp(v, OP_OpenRead, iCur, pTab->tnum); 261 } 262 sqliteVdbeAddOp(v, OP_MoveTo, iCur, 0); 263 264 /* Generate the OLD table 265 */ 266 sqliteVdbeAddOp(v, OP_Recno, iCur, 0); 267 sqliteVdbeAddOp(v, OP_RowData, iCur, 0); 268 sqliteVdbeAddOp(v, OP_PutIntKey, oldIdx, 0); 269 270 /* Generate the NEW table 271 */ 272 if( chngRecno ){ 273 sqliteExprCode(pParse, pRecnoExpr); 274 }else{ 275 sqliteVdbeAddOp(v, OP_Recno, iCur, 0); 276 } 277 for(i=0; i<pTab->nCol; i++){ 278 if( i==pTab->iPKey ){ 279 sqliteVdbeAddOp(v, OP_String, 0, 0); 280 continue; 281 } 282 j = aXRef[i]; 283 if( j<0 ){ 284 sqliteVdbeAddOp(v, OP_Column, iCur, i); 285 }else{ 286 sqliteExprCode(pParse, pChanges->a[j].pExpr); 287 } 288 } 289 sqliteVdbeAddOp(v, OP_MakeRecord, pTab->nCol, 0); 290 sqliteVdbeAddOp(v, OP_PutIntKey, newIdx, 0); 291 if( !isView ){ 292 sqliteVdbeAddOp(v, OP_Close, iCur, 0); 293 } 294 295 /* Fire the BEFORE and INSTEAD OF triggers 296 */ 297 if( sqliteCodeRowTrigger(pParse, TK_UPDATE, pChanges, TK_BEFORE, pTab, 298 newIdx, oldIdx, onError, addr) ){ 299 goto update_cleanup; 300 } 301 } 302 303 if( !isView ){ 304 /* 305 ** Open every index that needs updating. Note that if any 306 ** index could potentially invoke a REPLACE conflict resolution 307 ** action, then we need to open all indices because we might need 308 ** to be deleting some records. 309 */ 310 sqliteVdbeAddOp(v, OP_Integer, pTab->iDb, 0); 311 sqliteVdbeAddOp(v, OP_OpenWrite, iCur, pTab->tnum); 312 if( onError==OE_Replace ){ 313 openAll = 1; 314 }else{ 315 openAll = 0; 316 for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){ 317 if( pIdx->onError==OE_Replace ){ 318 openAll = 1; 319 break; 320 } 321 } 322 } 323 for(i=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){ 324 if( openAll || aIdxUsed[i] ){ 325 sqliteVdbeAddOp(v, OP_Integer, pIdx->iDb, 0); 326 sqliteVdbeAddOp(v, OP_OpenWrite, iCur+i+1, pIdx->tnum); 327 assert( pParse->nTab>iCur+i+1 ); 328 } 329 } 330 331 /* Loop over every record that needs updating. We have to load 332 ** the old data for each record to be updated because some columns 333 ** might not change and we will need to copy the old value. 334 ** Also, the old data is needed to delete the old index entires. 335 ** So make the cursor point at the old record. 336 */ 337 if( !row_triggers_exist ){ 338 sqliteVdbeAddOp(v, OP_ListRewind, 0, 0); 339 addr = sqliteVdbeAddOp(v, OP_ListRead, 0, 0); 340 sqliteVdbeAddOp(v, OP_Dup, 0, 0); 341 } 342 sqliteVdbeAddOp(v, OP_NotExists, iCur, addr); 343 344 /* If the record number will change, push the record number as it 345 ** will be after the update. (The old record number is currently 346 ** on top of the stack.) 347 */ 348 if( chngRecno ){ 349 sqliteExprCode(pParse, pRecnoExpr); 350 sqliteVdbeAddOp(v, OP_MustBeInt, 0, 0); 351 } 352 353 /* Compute new data for this record. 354 */ 355 for(i=0; i<pTab->nCol; i++){ 356 if( i==pTab->iPKey ){ 357 sqliteVdbeAddOp(v, OP_String, 0, 0); 358 continue; 359 } 360 j = aXRef[i]; 361 if( j<0 ){ 362 sqliteVdbeAddOp(v, OP_Column, iCur, i); 363 }else{ 364 sqliteExprCode(pParse, pChanges->a[j].pExpr); 365 } 366 } 367 368 /* Do constraint checks 369 */ 370 sqliteGenerateConstraintChecks(pParse, pTab, iCur, aIdxUsed, chngRecno, 1, 371 onError, addr); 372 373 /* Delete the old indices for the current record. 374 */ 375 sqliteGenerateRowIndexDelete(db, v, pTab, iCur, aIdxUsed); 376 377 /* If changing the record number, delete the old record. 378 */ 379 if( chngRecno ){ 380 sqliteVdbeAddOp(v, OP_Delete, iCur, 0); 381 } 382 383 /* Create the new index entries and the new record. 384 */ 385 sqliteCompleteInsertion(pParse, pTab, iCur, aIdxUsed, chngRecno, 1, -1); 386 } 387 388 /* Increment the row counter 389 */ 390 if( db->flags & SQLITE_CountRows && !pParse->trigStack){ 391 sqliteVdbeAddOp(v, OP_AddImm, 1, 0); 392 } 393 394 /* If there are triggers, close all the cursors after each iteration 395 ** through the loop. The fire the after triggers. 396 */ 397 if( row_triggers_exist ){ 398 if( !isView ){ 399 for(i=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){ 400 if( openAll || aIdxUsed[i] ) 401 sqliteVdbeAddOp(v, OP_Close, iCur+i+1, 0); 402 } 403 sqliteVdbeAddOp(v, OP_Close, iCur, 0); 404 pParse->nTab = iCur; 405 } 406 if( sqliteCodeRowTrigger(pParse, TK_UPDATE, pChanges, TK_AFTER, pTab, 407 newIdx, oldIdx, onError, addr) ){ 408 goto update_cleanup; 409 } 410 } 411 412 /* Repeat the above with the next record to be updated, until 413 ** all record selected by the WHERE clause have been updated. 414 */ 415 sqliteVdbeAddOp(v, OP_Goto, 0, addr); 416 sqliteVdbeChangeP2(v, addr, sqliteVdbeCurrentAddr(v)); 417 sqliteVdbeAddOp(v, OP_ListReset, 0, 0); 418 419 /* Close all tables if there were no FOR EACH ROW triggers */ 420 if( !row_triggers_exist ){ 421 for(i=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){ 422 if( openAll || aIdxUsed[i] ){ 423 sqliteVdbeAddOp(v, OP_Close, iCur+i+1, 0); 424 } 425 } 426 sqliteVdbeAddOp(v, OP_Close, iCur, 0); 427 pParse->nTab = iCur; 428 }else{ 429 sqliteVdbeAddOp(v, OP_Close, newIdx, 0); 430 sqliteVdbeAddOp(v, OP_Close, oldIdx, 0); 431 } 432 433 sqliteEndWriteOperation(pParse); 434 435 /* 436 ** Return the number of rows that were changed. 437 */ 438 if( db->flags & SQLITE_CountRows && !pParse->trigStack ){ 439 sqliteVdbeAddOp(v, OP_ColumnName, 0, 0); 440 sqliteVdbeChangeP3(v, -1, "rows updated", P3_STATIC); 441 sqliteVdbeAddOp(v, OP_Callback, 1, 0); 442 } 443 444 update_cleanup: 445 sqliteAuthContextPop(&sContext); 446 sqliteFree(apIdx); 447 sqliteFree(aXRef); 448 sqliteSrcListDelete(pTabList); 449 sqliteExprListDelete(pChanges); 450 sqliteExprDelete(pWhere); 451 return; 452 } 453