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 1.82 2004/06/10 10:50:45 danielk1977 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 sqlite3Update( 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 || sqlite3_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 = sqlite3SrcListLookup(pParse, pTabList); 69 if( pTab==0 ) goto update_cleanup; 70 before_triggers = sqlite3TriggersExist(pParse, pTab->pTrigger, 71 TK_UPDATE, TK_BEFORE, TK_ROW, pChanges); 72 after_triggers = sqlite3TriggersExist(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( sqlite3IsReadOnly(pParse, pTab, before_triggers) ){ 77 goto update_cleanup; 78 } 79 if( isView ){ 80 if( sqlite3ViewGetColumnNames(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( sqlite3ExprResolveIds(pParse, pTabList, 0, pChanges->a[i].pExpr) ){ 115 goto update_cleanup; 116 } 117 if( sqlite3ExprCheck(pParse, pChanges->a[i].pExpr, 0, 0) ){ 118 goto update_cleanup; 119 } 120 for(j=0; j<pTab->nCol; j++){ 121 if( sqlite3StrICmp(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( sqlite3IsRowid(pChanges->a[i].zName) ){ 132 chngRecno = 1; 133 pRecnoExpr = pChanges->a[i].pExpr; 134 }else{ 135 sqlite3ErrorMsg(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 = sqlite3AuthCheck(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 if( sqlite3CheckIndexCollSeq(pParse, pIdx) ) goto update_cleanup; 183 apIdx[nIdx++] = pIdx; 184 aIdxUsed[j] = 1; 185 }else{ 186 aIdxUsed[j] = 0; 187 } 188 } 189 190 /* Resolve the column names in all the expressions in the 191 ** WHERE clause. 192 */ 193 if( pWhere ){ 194 if( sqlite3ExprResolveIds(pParse, pTabList, 0, pWhere) ){ 195 goto update_cleanup; 196 } 197 if( sqlite3ExprCheck(pParse, pWhere, 0, 0) ){ 198 goto update_cleanup; 199 } 200 } 201 202 /* Start the view context 203 */ 204 if( isView ){ 205 sqlite3AuthContextPush(pParse, &sContext, pTab->zName); 206 } 207 208 /* Begin generating code. 209 */ 210 v = sqlite3GetVdbe(pParse); 211 if( v==0 ) goto update_cleanup; 212 sqlite3BeginWriteOperation(pParse, 1, pTab->iDb); 213 214 /* If we are trying to update a view, construct that view into 215 ** a temporary table. 216 */ 217 if( isView ){ 218 Select *pView; 219 pView = sqlite3SelectDup(pTab->pSelect); 220 sqlite3Select(pParse, pView, SRT_TempTable, iCur, 0, 0, 0, 0); 221 sqlite3SelectDelete(pView); 222 } 223 224 /* Begin the database scan 225 */ 226 pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, 1, 0); 227 if( pWInfo==0 ) goto update_cleanup; 228 229 /* Remember the index of every item to be updated. 230 */ 231 sqlite3VdbeAddOp(v, OP_ListWrite, 0, 0); 232 233 /* End the database scan loop. 234 */ 235 sqlite3WhereEnd(pWInfo); 236 237 /* Initialize the count of updated rows 238 */ 239 if( db->flags & SQLITE_CountRows && !pParse->trigStack ){ 240 sqlite3VdbeAddOp(v, OP_Integer, 0, 0); 241 } 242 243 if( row_triggers_exist ){ 244 /* Create pseudo-tables for NEW and OLD 245 */ 246 sqlite3VdbeAddOp(v, OP_OpenPseudo, oldIdx, 0); 247 sqlite3VdbeAddOp(v, OP_SetNumColumns, oldIdx, pTab->nCol); 248 sqlite3VdbeAddOp(v, OP_OpenPseudo, newIdx, 0); 249 sqlite3VdbeAddOp(v, OP_SetNumColumns, newIdx, pTab->nCol); 250 251 /* The top of the update loop for when there are triggers. 252 */ 253 sqlite3VdbeAddOp(v, OP_ListRewind, 0, 0); 254 addr = sqlite3VdbeAddOp(v, OP_ListRead, 0, 0); 255 sqlite3VdbeAddOp(v, OP_Dup, 0, 0); 256 257 /* Open a cursor and make it point to the record that is 258 ** being updated. 259 */ 260 sqlite3VdbeAddOp(v, OP_Dup, 0, 0); 261 if( !isView ){ 262 sqlite3VdbeAddOp(v, OP_Integer, pTab->iDb, 0); 263 sqlite3VdbeAddOp(v, OP_OpenRead, iCur, pTab->tnum); 264 sqlite3VdbeAddOp(v, OP_SetNumColumns, iCur, pTab->nCol); 265 } 266 sqlite3VdbeAddOp(v, OP_MoveGe, iCur, 0); 267 268 /* Generate the OLD table 269 */ 270 sqlite3VdbeAddOp(v, OP_Recno, iCur, 0); 271 sqlite3VdbeAddOp(v, OP_RowData, iCur, 0); 272 sqlite3VdbeAddOp(v, OP_PutIntKey, oldIdx, 0); 273 274 /* Generate the NEW table 275 */ 276 if( chngRecno ){ 277 sqlite3ExprCode(pParse, pRecnoExpr); 278 }else{ 279 sqlite3VdbeAddOp(v, OP_Recno, iCur, 0); 280 } 281 for(i=0; i<pTab->nCol; i++){ 282 if( i==pTab->iPKey ){ 283 sqlite3VdbeAddOp(v, OP_String8, 0, 0); 284 continue; 285 } 286 j = aXRef[i]; 287 if( j<0 ){ 288 sqlite3VdbeAddOp(v, OP_Column, iCur, i); 289 }else{ 290 sqlite3ExprCode(pParse, pChanges->a[j].pExpr); 291 } 292 } 293 sqlite3VdbeAddOp(v, OP_MakeRecord, pTab->nCol, 0); 294 if( !isView ){ 295 sqlite3TableAffinityStr(v, pTab); 296 } 297 if( pParse->nErr ) goto update_cleanup; 298 sqlite3VdbeAddOp(v, OP_PutIntKey, newIdx, 0); 299 if( !isView ){ 300 sqlite3VdbeAddOp(v, OP_Close, iCur, 0); 301 } 302 303 /* Fire the BEFORE and INSTEAD OF triggers 304 */ 305 if( sqlite3CodeRowTrigger(pParse, TK_UPDATE, pChanges, TK_BEFORE, pTab, 306 newIdx, oldIdx, onError, addr) ){ 307 goto update_cleanup; 308 } 309 } 310 311 if( !isView ){ 312 /* 313 ** Open every index that needs updating. Note that if any 314 ** index could potentially invoke a REPLACE conflict resolution 315 ** action, then we need to open all indices because we might need 316 ** to be deleting some records. 317 */ 318 sqlite3VdbeAddOp(v, OP_Integer, pTab->iDb, 0); 319 sqlite3VdbeAddOp(v, OP_OpenWrite, iCur, pTab->tnum); 320 sqlite3VdbeAddOp(v, OP_SetNumColumns, iCur, pTab->nCol); 321 if( onError==OE_Replace ){ 322 openAll = 1; 323 }else{ 324 openAll = 0; 325 for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){ 326 if( pIdx->onError==OE_Replace ){ 327 openAll = 1; 328 break; 329 } 330 } 331 } 332 for(i=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){ 333 if( openAll || aIdxUsed[i] ){ 334 sqlite3VdbeAddOp(v, OP_Integer, pIdx->iDb, 0); 335 sqlite3VdbeOp3(v, OP_OpenWrite, iCur+i+1, pIdx->tnum, 336 (char*)&pIdx->keyInfo, P3_KEYINFO); 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 sqlite3VdbeAddOp(v, OP_ListRewind, 0, 0); 349 addr = sqlite3VdbeAddOp(v, OP_ListRead, 0, 0); 350 sqlite3VdbeAddOp(v, OP_Dup, 0, 0); 351 } 352 sqlite3VdbeAddOp(v, OP_NotExists, iCur, addr); 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 sqlite3ExprCode(pParse, pRecnoExpr); 360 sqlite3VdbeAddOp(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 sqlite3VdbeAddOp(v, OP_String8, 0, 0); 368 continue; 369 } 370 j = aXRef[i]; 371 if( j<0 ){ 372 sqlite3VdbeAddOp(v, OP_Column, iCur, i); 373 }else{ 374 sqlite3ExprCode(pParse, pChanges->a[j].pExpr); 375 } 376 } 377 378 /* Do constraint checks 379 */ 380 sqlite3GenerateConstraintChecks(pParse, pTab, iCur, aIdxUsed, chngRecno, 1, 381 onError, addr); 382 383 /* Delete the old indices for the current record. 384 */ 385 sqlite3GenerateRowIndexDelete(db, v, pTab, iCur, aIdxUsed); 386 387 /* If changing the record number, delete the old record. 388 */ 389 if( chngRecno ){ 390 sqlite3VdbeAddOp(v, OP_Delete, iCur, 0); 391 } 392 393 /* Create the new index entries and the new record. 394 */ 395 sqlite3CompleteInsertion(pParse, pTab, iCur, aIdxUsed, chngRecno, 1, -1); 396 } 397 398 /* Increment the row counter 399 */ 400 if( db->flags & SQLITE_CountRows && !pParse->trigStack){ 401 sqlite3VdbeAddOp(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 sqlite3VdbeAddOp(v, OP_Close, iCur+i+1, 0); 412 } 413 sqlite3VdbeAddOp(v, OP_Close, iCur, 0); 414 pParse->nTab = iCur; 415 } 416 if( sqlite3CodeRowTrigger(pParse, TK_UPDATE, pChanges, TK_AFTER, pTab, 417 newIdx, oldIdx, onError, addr) ){ 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 sqlite3VdbeAddOp(v, OP_Goto, 0, addr); 426 sqlite3VdbeChangeP2(v, addr, sqlite3VdbeCurrentAddr(v)); 427 sqlite3VdbeAddOp(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 sqlite3VdbeAddOp(v, OP_Close, iCur+i+1, 0); 434 } 435 } 436 sqlite3VdbeAddOp(v, OP_Close, iCur, 0); 437 pParse->nTab = iCur; 438 }else{ 439 sqlite3VdbeAddOp(v, OP_Close, newIdx, 0); 440 sqlite3VdbeAddOp(v, OP_Close, oldIdx, 0); 441 } 442 443 sqlite3VdbeAddOp(v, OP_SetCounts, 0, 0); 444 sqlite3EndWriteOperation(pParse); 445 446 /* 447 ** Return the number of rows that were changed. 448 */ 449 if( db->flags & SQLITE_CountRows && !pParse->trigStack ){ 450 sqlite3VdbeAddOp(v, OP_Callback, 1, 0); 451 sqlite3VdbeSetNumCols(v, 1); 452 sqlite3VdbeSetColName(v, 0, "rows updated", P3_STATIC); 453 } 454 455 update_cleanup: 456 sqlite3AuthContextPop(&sContext); 457 sqliteFree(apIdx); 458 sqliteFree(aXRef); 459 sqlite3SrcListDelete(pTabList); 460 sqlite3ExprListDelete(pChanges); 461 sqlite3ExprDelete(pWhere); 462 return; 463 } 464