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 1.207 2009/08/08 18:01:08 drh Exp $ 16 */ 17 #include "sqliteInt.h" 18 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 */ 29 ); 30 #endif /* SQLITE_OMIT_VIRTUALTABLE */ 31 32 /* 33 ** The most recently coded instruction was an OP_Column to retrieve the 34 ** i-th column of table pTab. This routine sets the P4 parameter of the 35 ** OP_Column to the default value, if any. 36 ** 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 P4 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 P4 value is not required. 45 ** 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.) 51 ** 52 ** Therefore, the P4 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. 56 ** 57 ** If parameter iReg is not negative, code an OP_RealAffinity instruction 58 ** on register iReg. This is used when an equivalent integer value is 59 ** stored in place of an 8-byte floating point value in order to save 60 ** space. 61 */ 62 void sqlite3ColumnDefault(Vdbe *v, Table *pTab, int i, int iReg){ 63 assert( pTab!=0 ); 64 if( !pTab->pSelect ){ 65 sqlite3_value *pValue; 66 u8 enc = ENC(sqlite3VdbeDb(v)); 67 Column *pCol = &pTab->aCol[i]; 68 VdbeComment((v, "%s.%s", pTab->zName, pCol->zName)); 69 assert( i<pTab->nCol ); 70 sqlite3ValueFromExpr(sqlite3VdbeDb(v), pCol->pDflt, enc, 71 pCol->affinity, &pValue); 72 if( pValue ){ 73 sqlite3VdbeChangeP4(v, -1, (const char *)pValue, P4_MEM); 74 } 75 #ifndef SQLITE_OMIT_FLOATING_POINT 76 if( iReg>=0 && pTab->aCol[i].affinity==SQLITE_AFF_REAL ){ 77 sqlite3VdbeAddOp1(v, OP_RealAffinity, iReg); 78 } 79 #endif 80 } 81 } 82 83 /* 84 ** Process an UPDATE statement. 85 ** 86 ** UPDATE OR IGNORE table_wxyz SET a=b, c=d WHERE e<5 AND f NOT NULL; 87 ** \_______/ \________/ \______/ \________________/ 88 * onError pTabList pChanges pWhere 89 */ 90 void sqlite3Update( 91 Parse *pParse, /* The parser context */ 92 SrcList *pTabList, /* The table in which we should change things */ 93 ExprList *pChanges, /* Things to be changed */ 94 Expr *pWhere, /* The WHERE clause. May be null */ 95 int onError /* How to handle constraint errors */ 96 ){ 97 int i, j; /* Loop counters */ 98 Table *pTab; /* The table to be updated */ 99 int addr = 0; /* VDBE instruction address of the start of the loop */ 100 WhereInfo *pWInfo; /* Information about the WHERE clause */ 101 Vdbe *v; /* The virtual database engine */ 102 Index *pIdx; /* For looping over indices */ 103 int nIdx; /* Number of indices that need updating */ 104 int iCur; /* VDBE Cursor number of pTab */ 105 sqlite3 *db; /* The database structure */ 106 int *aRegIdx = 0; /* One register assigned to each index to be updated */ 107 int *aXRef = 0; /* aXRef[i] is the index in pChanges->a[] of the 108 ** an expression for the i-th column of the table. 109 ** aXRef[i]==-1 if the i-th column is not changed. */ 110 int chngRowid; /* True if the record number is being changed */ 111 Expr *pRowidExpr = 0; /* Expression defining the new record number */ 112 int openAll = 0; /* True if all indices need to be opened */ 113 AuthContext sContext; /* The authorization context */ 114 NameContext sNC; /* The name-context to resolve expressions in */ 115 int iDb; /* Database containing the table being updated */ 116 int j1; /* Addresses of jump instructions */ 117 int okOnePass; /* True for one-pass algorithm without the FIFO */ 118 int hasFK; /* True if foreign key processing is required */ 119 120 #ifndef SQLITE_OMIT_TRIGGER 121 int isView; /* Trying to update a view */ 122 Trigger *pTrigger; /* List of triggers on pTab, if required */ 123 #endif 124 125 /* Register Allocations */ 126 int regRowCount = 0; /* A count of rows changed */ 127 int regOldRowid; /* The old rowid */ 128 int regNewRowid; /* The new rowid */ 129 int regNew; 130 int regOld = 0; 131 int regRowSet = 0; /* Rowset of rows to be updated */ 132 int regRec; /* Register used for new table record to insert */ 133 134 memset(&sContext, 0, sizeof(sContext)); 135 db = pParse->db; 136 if( pParse->nErr || db->mallocFailed ){ 137 goto update_cleanup; 138 } 139 assert( pTabList->nSrc==1 ); 140 141 /* Locate the table which we want to update. 142 */ 143 pTab = sqlite3SrcListLookup(pParse, pTabList); 144 if( pTab==0 ) goto update_cleanup; 145 iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema); 146 147 /* Figure out if we have any triggers and if the table being 148 ** updated is a view. 149 */ 150 #ifndef SQLITE_OMIT_TRIGGER 151 pTrigger = sqlite3TriggersExist(pParse, pTab, TK_UPDATE, pChanges, 0); 152 isView = pTab->pSelect!=0; 153 #else 154 # define pTrigger 0 155 # define isView 0 156 #endif 157 #ifdef SQLITE_OMIT_VIEW 158 # undef isView 159 # define isView 0 160 #endif 161 162 if( sqlite3ViewGetColumnNames(pParse, pTab) ){ 163 goto update_cleanup; 164 } 165 if( sqlite3IsReadOnly(pParse, pTab, (pTrigger?1:0)) ){ 166 goto update_cleanup; 167 } 168 aXRef = sqlite3DbMallocRaw(db, sizeof(int) * pTab->nCol ); 169 if( aXRef==0 ) goto update_cleanup; 170 for(i=0; i<pTab->nCol; i++) aXRef[i] = -1; 171 172 /* Allocate a cursors for the main database table and for all indices. 173 ** The index cursors might not be used, but if they are used they 174 ** need to occur right after the database cursor. So go ahead and 175 ** allocate enough space, just in case. 176 */ 177 pTabList->a[0].iCursor = iCur = pParse->nTab++; 178 for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){ 179 pParse->nTab++; 180 } 181 182 /* Initialize the name-context */ 183 memset(&sNC, 0, sizeof(sNC)); 184 sNC.pParse = pParse; 185 sNC.pSrcList = pTabList; 186 187 /* Resolve the column names in all the expressions of the 188 ** of the UPDATE statement. Also find the column index 189 ** for each column to be updated in the pChanges array. For each 190 ** column to be updated, make sure we have authorization to change 191 ** that column. 192 */ 193 chngRowid = 0; 194 for(i=0; i<pChanges->nExpr; i++){ 195 if( sqlite3ResolveExprNames(&sNC, pChanges->a[i].pExpr) ){ 196 goto update_cleanup; 197 } 198 for(j=0; j<pTab->nCol; j++){ 199 if( sqlite3StrICmp(pTab->aCol[j].zName, pChanges->a[i].zName)==0 ){ 200 if( j==pTab->iPKey ){ 201 chngRowid = 1; 202 pRowidExpr = pChanges->a[i].pExpr; 203 } 204 aXRef[j] = i; 205 break; 206 } 207 } 208 if( j>=pTab->nCol ){ 209 if( sqlite3IsRowid(pChanges->a[i].zName) ){ 210 chngRowid = 1; 211 pRowidExpr = pChanges->a[i].pExpr; 212 }else{ 213 sqlite3ErrorMsg(pParse, "no such column: %s", pChanges->a[i].zName); 214 goto update_cleanup; 215 } 216 } 217 #ifndef SQLITE_OMIT_AUTHORIZATION 218 { 219 int rc; 220 rc = sqlite3AuthCheck(pParse, SQLITE_UPDATE, pTab->zName, 221 pTab->aCol[j].zName, db->aDb[iDb].zName); 222 if( rc==SQLITE_DENY ){ 223 goto update_cleanup; 224 }else if( rc==SQLITE_IGNORE ){ 225 aXRef[j] = -1; 226 } 227 } 228 #endif 229 } 230 231 hasFK = sqlite3FkRequired(pParse, pTab, aXRef, chngRowid); 232 233 /* Allocate memory for the array aRegIdx[]. There is one entry in the 234 ** array for each index associated with table being updated. Fill in 235 ** the value with a register number for indices that are to be used 236 ** and with zero for unused indices. 237 */ 238 for(nIdx=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, nIdx++){} 239 if( nIdx>0 ){ 240 aRegIdx = sqlite3DbMallocRaw(db, sizeof(Index*) * nIdx ); 241 if( aRegIdx==0 ) goto update_cleanup; 242 } 243 for(j=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, j++){ 244 int reg; 245 if( chngRowid ){ 246 reg = ++pParse->nMem; 247 }else{ 248 reg = 0; 249 for(i=0; i<pIdx->nColumn; i++){ 250 if( aXRef[pIdx->aiColumn[i]]>=0 ){ 251 reg = ++pParse->nMem; 252 break; 253 } 254 } 255 } 256 aRegIdx[j] = reg; 257 } 258 259 /* 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); 264 265 #ifndef SQLITE_OMIT_VIRTUALTABLE 266 /* Virtual tables must be handled separately */ 267 if( IsVirtual(pTab) ){ 268 updateVirtualTable(pParse, pTabList, pTab, pChanges, pRowidExpr, aXRef, 269 pWhere); 270 pWhere = 0; 271 pTabList = 0; 272 goto update_cleanup; 273 } 274 #endif 275 276 /* Allocate required registers. */ 277 regOldRowid = regNewRowid = ++pParse->nMem; 278 if( pTrigger || hasFK ){ 279 regOld = pParse->nMem + 1; 280 pParse->nMem += pTab->nCol; 281 } 282 if( chngRowid || pTrigger || hasFK ){ 283 regNewRowid = ++pParse->nMem; 284 } 285 regNew = pParse->nMem + 1; 286 pParse->nMem += pTab->nCol; 287 regRec = ++pParse->nMem; 288 289 /* Start the view context. */ 290 if( isView ){ 291 sqlite3AuthContextPush(pParse, &sContext, pTab->zName); 292 } 293 294 /* If we are trying to update a view, realize that view into 295 ** a ephemeral table. 296 */ 297 #if !defined(SQLITE_OMIT_VIEW) && !defined(SQLITE_OMIT_TRIGGER) 298 if( isView ){ 299 sqlite3MaterializeView(pParse, pTab, pWhere, iCur); 300 } 301 #endif 302 303 /* Resolve the column names in all the expressions in the 304 ** WHERE clause. 305 */ 306 if( sqlite3ResolveExprNames(&sNC, pWhere) ){ 307 goto update_cleanup; 308 } 309 310 /* Begin the database scan 311 */ 312 sqlite3VdbeAddOp2(v, OP_Null, 0, regOldRowid); 313 pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere,0, WHERE_ONEPASS_DESIRED); 314 if( pWInfo==0 ) goto update_cleanup; 315 okOnePass = pWInfo->okOnePass; 316 317 /* Remember the rowid of every item to be updated. 318 */ 319 sqlite3VdbeAddOp2(v, OP_Rowid, iCur, regOldRowid); 320 if( !okOnePass ){ 321 regRowSet = ++pParse->nMem; 322 sqlite3VdbeAddOp2(v, OP_RowSetAdd, regRowSet, regOldRowid); 323 } 324 325 /* End the database scan loop. 326 */ 327 sqlite3WhereEnd(pWInfo); 328 329 /* Initialize the count of updated rows 330 */ 331 if( (db->flags & SQLITE_CountRows) && !pParse->pTriggerTab ){ 332 regRowCount = ++pParse->nMem; 333 sqlite3VdbeAddOp2(v, OP_Integer, 0, regRowCount); 334 } 335 336 if( !isView ){ 337 /* 338 ** Open every index that needs updating. Note that if any 339 ** index could potentially invoke a REPLACE conflict resolution 340 ** action, then we need to open all indices because we might need 341 ** to be deleting some records. 342 */ 343 if( !okOnePass ) sqlite3OpenTable(pParse, iCur, iDb, pTab, OP_OpenWrite); 344 if( onError==OE_Replace ){ 345 openAll = 1; 346 }else{ 347 openAll = 0; 348 for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){ 349 if( pIdx->onError==OE_Replace ){ 350 openAll = 1; 351 break; 352 } 353 } 354 } 355 for(i=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){ 356 if( openAll || aRegIdx[i]>0 ){ 357 KeyInfo *pKey = sqlite3IndexKeyinfo(pParse, pIdx); 358 sqlite3VdbeAddOp4(v, OP_OpenWrite, iCur+i+1, pIdx->tnum, iDb, 359 (char*)pKey, P4_KEYINFO_HANDOFF); 360 assert( pParse->nTab>iCur+i+1 ); 361 } 362 } 363 } 364 365 /* Top of the update loop */ 366 if( okOnePass ){ 367 int a1 = sqlite3VdbeAddOp1(v, OP_NotNull, regOldRowid); 368 addr = sqlite3VdbeAddOp0(v, OP_Goto); 369 sqlite3VdbeJumpHere(v, a1); 370 }else{ 371 addr = sqlite3VdbeAddOp3(v, OP_RowSetRead, regRowSet, 0, regOldRowid); 372 } 373 374 /* Make cursor iCur point to the record that is being updated. If 375 ** this record does not exist for some reason (deleted by a trigger, 376 ** for example, then jump to the next iteration of the RowSet loop. */ 377 sqlite3VdbeAddOp3(v, OP_NotExists, iCur, addr, regOldRowid); 378 379 /* If the record number will change, set register regNewRowid to 380 ** contain the new value. If the record number is not being modified, 381 ** then regNewRowid is the same register as regOldRowid, which is 382 ** already populated. */ 383 assert( chngRowid || pTrigger || hasFK || regOldRowid==regNewRowid ); 384 if( chngRowid ){ 385 sqlite3ExprCode(pParse, pRowidExpr, regNewRowid); 386 sqlite3VdbeAddOp1(v, OP_MustBeInt, regNewRowid); 387 } 388 389 /* If there are triggers on this table, populate an array of registers 390 ** with the required old.* column data. */ 391 if( hasFK || pTrigger ){ 392 u32 oldmask = (hasFK ? sqlite3FkOldmask(pParse, pTab) : 0); 393 oldmask |= sqlite3TriggerOldmask(pParse, pTrigger, pChanges, pTab, onError); 394 for(i=0; i<pTab->nCol; i++){ 395 if( aXRef[i]<0 || oldmask==0xffffffff || (oldmask & (1<<i)) ){ 396 sqlite3VdbeAddOp3(v, OP_Column, iCur, i, regOld+i); 397 sqlite3ColumnDefault(v, pTab, i, regOld+i); 398 }else{ 399 sqlite3VdbeAddOp2(v, OP_Null, 0, regOld+i); 400 } 401 } 402 if( chngRowid==0 ){ 403 sqlite3VdbeAddOp2(v, OP_Copy, regOldRowid, regNewRowid); 404 } 405 } 406 407 /* Populate the array of registers beginning at regNew with the new 408 ** row data. This array is used to check constaints, create the new 409 ** table and index records, and as the values for any new.* references 410 ** made by triggers. */ 411 for(i=0; i<pTab->nCol; i++){ 412 if( i==pTab->iPKey ){ 413 sqlite3VdbeAddOp2(v, OP_Null, 0, regNew+i); 414 }else{ 415 j = aXRef[i]; 416 if( j<0 ){ 417 sqlite3VdbeAddOp3(v, OP_Column, iCur, i, regNew+i); 418 sqlite3ColumnDefault(v, pTab, i, regNew+i); 419 }else{ 420 sqlite3ExprCode(pParse, pChanges->a[j].pExpr, regNew+i); 421 } 422 } 423 } 424 425 /* Fire any BEFORE UPDATE triggers. This happens before constraints are 426 ** verified. One could argue that this is wrong. */ 427 if( pTrigger ){ 428 sqlite3VdbeAddOp2(v, OP_Affinity, regNew, pTab->nCol); 429 sqlite3TableAffinityStr(v, pTab); 430 sqlite3CodeRowTrigger(pParse, pTrigger, TK_UPDATE, pChanges, 431 TRIGGER_BEFORE, pTab, regOldRowid, onError, addr); 432 433 /* The row-trigger may have deleted the row being updated. In this 434 ** case, jump to the next row. No updates or AFTER triggers are 435 ** required. This behaviour - what happens when the row being updated 436 ** is deleted or renamed by a BEFORE trigger - is left undefined in the 437 ** documentation. */ 438 sqlite3VdbeAddOp3(v, OP_NotExists, iCur, addr, regOldRowid); 439 } 440 441 if( !isView ){ 442 443 /* Do constraint checks. */ 444 sqlite3GenerateConstraintChecks(pParse, pTab, iCur, regNewRowid, 445 aRegIdx, (chngRowid?regOldRowid:0), 1, onError, addr, 0); 446 447 /* Do FK constraint checks. */ 448 if( hasFK ){ 449 sqlite3FkCheck(pParse, pTab, regOldRowid, 0); 450 } 451 452 /* Delete the index entries associated with the current record. */ 453 j1 = sqlite3VdbeAddOp3(v, OP_NotExists, iCur, 0, regOldRowid); 454 sqlite3GenerateRowIndexDelete(pParse, pTab, iCur, aRegIdx); 455 456 /* If changing the record number, delete the old record. */ 457 if( hasFK || chngRowid ){ 458 sqlite3VdbeAddOp2(v, OP_Delete, iCur, 0); 459 } 460 sqlite3VdbeJumpHere(v, j1); 461 462 if( hasFK ){ 463 sqlite3FkCheck(pParse, pTab, 0, regNewRowid); 464 } 465 466 /* Insert the new index entries and the new record. */ 467 sqlite3CompleteInsertion(pParse, pTab, iCur, regNewRowid, aRegIdx, 1, 0, 0); 468 469 /* Do any ON CASCADE, SET NULL or SET DEFAULT operations required to 470 ** handle rows (possibly in other tables) that refer via a foreign key 471 ** to the row just updated. */ 472 if( hasFK ){ 473 sqlite3FkActions(pParse, pTab, pChanges, regOldRowid); 474 } 475 } 476 477 /* Increment the row counter 478 */ 479 if( (db->flags & SQLITE_CountRows) && !pParse->pTriggerTab){ 480 sqlite3VdbeAddOp2(v, OP_AddImm, regRowCount, 1); 481 } 482 483 sqlite3CodeRowTrigger(pParse, pTrigger, TK_UPDATE, pChanges, 484 TRIGGER_AFTER, pTab, regOldRowid, onError, addr); 485 486 /* Repeat the above with the next record to be updated, until 487 ** all record selected by the WHERE clause have been updated. 488 */ 489 sqlite3VdbeAddOp2(v, OP_Goto, 0, addr); 490 sqlite3VdbeJumpHere(v, addr); 491 492 /* Close all tables */ 493 for(i=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){ 494 if( openAll || aRegIdx[i]>0 ){ 495 sqlite3VdbeAddOp2(v, OP_Close, iCur+i+1, 0); 496 } 497 } 498 sqlite3VdbeAddOp2(v, OP_Close, iCur, 0); 499 500 /* Update the sqlite_sequence table by storing the content of the 501 ** maximum rowid counter values recorded while inserting into 502 ** autoincrement tables. 503 */ 504 if( pParse->nested==0 && pParse->pTriggerTab==0 ){ 505 sqlite3AutoincrementEnd(pParse); 506 } 507 508 /* 509 ** Return the number of rows that were changed. If this routine is 510 ** generating code because of a call to sqlite3NestedParse(), do not 511 ** invoke the callback function. 512 */ 513 if( (db->flags&SQLITE_CountRows) && !pParse->pTriggerTab && !pParse->nested ){ 514 sqlite3VdbeAddOp2(v, OP_ResultRow, regRowCount, 1); 515 sqlite3VdbeSetNumCols(v, 1); 516 sqlite3VdbeSetColName(v, 0, COLNAME_NAME, "rows updated", SQLITE_STATIC); 517 } 518 519 update_cleanup: 520 sqlite3AuthContextPop(&sContext); 521 sqlite3DbFree(db, aRegIdx); 522 sqlite3DbFree(db, aXRef); 523 sqlite3SrcListDelete(db, pTabList); 524 sqlite3ExprListDelete(db, pChanges); 525 sqlite3ExprDelete(db, pWhere); 526 return; 527 } 528 /* Make sure "isView" and other macros defined above are undefined. Otherwise 529 ** thely may interfere with compilation of other functions in this file 530 ** (or in another file, if this file becomes part of the amalgamation). */ 531 #ifdef isView 532 #undef isView 533 #endif 534 #ifdef pTrigger 535 #undef pTrigger 536 #endif 537 538 #ifndef SQLITE_OMIT_VIRTUALTABLE 539 /* 540 ** Generate code for an UPDATE of a virtual table. 541 ** 542 ** The strategy is that we create an ephemerial table that contains 543 ** for each row to be changed: 544 ** 545 ** (A) The original rowid of that row. 546 ** (B) The revised rowid for the row. (note1) 547 ** (C) The content of every column in the row. 548 ** 549 ** Then we loop over this ephemeral table and for each row in 550 ** the ephermeral table call VUpdate. 551 ** 552 ** When finished, drop the ephemeral table. 553 ** 554 ** (note1) Actually, if we know in advance that (A) is always the same 555 ** as (B) we only store (A), then duplicate (A) when pulling 556 ** it out of the ephemeral table before calling VUpdate. 557 */ 558 static void updateVirtualTable( 559 Parse *pParse, /* The parsing context */ 560 SrcList *pSrc, /* The virtual table to be modified */ 561 Table *pTab, /* The virtual table */ 562 ExprList *pChanges, /* The columns to change in the UPDATE statement */ 563 Expr *pRowid, /* Expression used to recompute the rowid */ 564 int *aXRef, /* Mapping from columns of pTab to entries in pChanges */ 565 Expr *pWhere /* WHERE clause of the UPDATE statement */ 566 ){ 567 Vdbe *v = pParse->pVdbe; /* Virtual machine under construction */ 568 ExprList *pEList = 0; /* The result set of the SELECT statement */ 569 Select *pSelect = 0; /* The SELECT statement */ 570 Expr *pExpr; /* Temporary expression */ 571 int ephemTab; /* Table holding the result of the SELECT */ 572 int i; /* Loop counter */ 573 int addr; /* Address of top of loop */ 574 int iReg; /* First register in set passed to OP_VUpdate */ 575 sqlite3 *db = pParse->db; /* Database connection */ 576 const char *pVTab = (const char*)sqlite3GetVTable(db, pTab); 577 SelectDest dest; 578 579 /* Construct the SELECT statement that will find the new values for 580 ** all updated rows. 581 */ 582 pEList = sqlite3ExprListAppend(pParse, 0, 583 sqlite3CreateIdExpr(pParse, "_rowid_")); 584 if( pRowid ){ 585 pEList = sqlite3ExprListAppend(pParse, pEList, 586 sqlite3ExprDup(db, pRowid, 0)); 587 } 588 assert( pTab->iPKey<0 ); 589 for(i=0; i<pTab->nCol; i++){ 590 if( aXRef[i]>=0 ){ 591 pExpr = sqlite3ExprDup(db, pChanges->a[aXRef[i]].pExpr, 0); 592 }else{ 593 pExpr = sqlite3CreateIdExpr(pParse, pTab->aCol[i].zName); 594 } 595 pEList = sqlite3ExprListAppend(pParse, pEList, pExpr); 596 } 597 pSelect = sqlite3SelectNew(pParse, pEList, pSrc, pWhere, 0, 0, 0, 0, 0, 0); 598 599 /* Create the ephemeral table into which the update results will 600 ** be stored. 601 */ 602 assert( v ); 603 ephemTab = pParse->nTab++; 604 sqlite3VdbeAddOp2(v, OP_OpenEphemeral, ephemTab, pTab->nCol+1+(pRowid!=0)); 605 606 /* fill the ephemeral table 607 */ 608 sqlite3SelectDestInit(&dest, SRT_Table, ephemTab); 609 sqlite3Select(pParse, pSelect, &dest); 610 611 /* Generate code to scan the ephemeral table and call VUpdate. */ 612 iReg = ++pParse->nMem; 613 pParse->nMem += pTab->nCol+1; 614 addr = sqlite3VdbeAddOp2(v, OP_Rewind, ephemTab, 0); 615 sqlite3VdbeAddOp3(v, OP_Column, ephemTab, 0, iReg); 616 sqlite3VdbeAddOp3(v, OP_Column, ephemTab, (pRowid?1:0), iReg+1); 617 for(i=0; i<pTab->nCol; i++){ 618 sqlite3VdbeAddOp3(v, OP_Column, ephemTab, i+1+(pRowid!=0), iReg+2+i); 619 } 620 sqlite3VtabMakeWritable(pParse, pTab); 621 sqlite3VdbeAddOp4(v, OP_VUpdate, 0, pTab->nCol+2, iReg, pVTab, P4_VTAB); 622 sqlite3MayAbort(pParse); 623 sqlite3VdbeAddOp2(v, OP_Next, ephemTab, addr+1); 624 sqlite3VdbeJumpHere(v, addr); 625 sqlite3VdbeAddOp2(v, OP_Close, ephemTab, 0); 626 627 /* Cleanup */ 628 sqlite3SelectDelete(db, pSelect); 629 } 630 #endif /* SQLITE_OMIT_VIRTUALTABLE */ 631