src/update.c

   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 #include "sqliteInt.h"
  16
  17 #ifndef SQLITE_OMIT_VIRTUALTABLE
  18 /* Forward declaration */
  19 static void updateVirtualTable(
  20   Parse *pParse,       /* The parsing context */
  21   SrcList *pSrc,       /* The virtual table to be modified */
  22   Table *pTab,         /* The virtual table */
  23   ExprList *pChanges,  /* The columns to change in the UPDATE statement */
  24   Expr *pRowidExpr,    /* Expression used to recompute the rowid */
  25   int *aXRef,          /* Mapping from columns of pTab to entries in pChanges */
  26   Expr *pWhere,        /* WHERE clause of the UPDATE statement */
  27   int onError          /* ON CONFLICT strategy */
  28 );
  29 #endif /* SQLITE_OMIT_VIRTUALTABLE */
  30
  31 /*
  32 ** The most recently coded instruction was an OP_Column to retrieve the
  33 ** i-th column of table pTab. This routine sets the P4 parameter of the
  34 ** OP_Column to the default value, if any.
  35 **
  36 ** The default value of a column is specified by a DEFAULT clause in the
  37 ** column definition. This was either supplied by the user when the table
  38 ** was created, or added later to the table definition by an ALTER TABLE
  39 ** command. If the latter, then the row-records in the table btree on disk
  40 ** may not contain a value for the column and the default value, taken
  41 ** from the P4 parameter of the OP_Column instruction, is returned instead.
  42 ** If the former, then all row-records are guaranteed to include a value
  43 ** for the column and the P4 value is not required.
  44 **
  45 ** Column definitions created by an ALTER TABLE command may only have
  46 ** literal default values specified: a number, null or a string. (If a more
  47 ** complicated default expression value was provided, it is evaluated
  48 ** when the ALTER TABLE is executed and one of the literal values written
  49 ** into the sqlite_schema table.)
  50 **
  51 ** Therefore, the P4 parameter is only required if the default value for
  52 ** the column is a literal number, string or null. The sqlite3ValueFromExpr()
  53 ** function is capable of transforming these types of expressions into
  54 ** sqlite3_value objects.
  55 **
  56 ** If column as REAL affinity and the table is an ordinary b-tree table
  57 ** (not a virtual table) then the value might have been stored as an
  58 ** integer.  In that case, add an OP_RealAffinity opcode to make sure
  59 ** it has been converted into REAL.
  60 */
  61 void sqlite3ColumnDefault(Vdbe *v, Table *pTab, int i, int iReg){
  62   assert( pTab!=0 );
  63   if( !IsView(pTab) ){
  64     sqlite3_value *pValue = 0;
  65     u8 enc = ENC(sqlite3VdbeDb(v));
  66     Column *pCol = &pTab->aCol[i];
  67     VdbeComment((v, "%s.%s", pTab->zName, pCol->zCnName));
  68     assert( i<pTab->nCol );
  69     sqlite3ValueFromExpr(sqlite3VdbeDb(v),
  70                          sqlite3ColumnExpr(pTab,pCol), enc,
  71                          pCol->affinity, &pValue);
  72     if( pValue ){
  73       sqlite3VdbeAppendP4(v, pValue, P4_MEM);
  74     }
  75   }
  76 #ifndef SQLITE_OMIT_FLOATING_POINT
  77   if( pTab->aCol[i].affinity==SQLITE_AFF_REAL && !IsVirtual(pTab) ){
  78     sqlite3VdbeAddOp1(v, OP_RealAffinity, iReg);
  79   }
  80 #endif
  81 }
  82
  83 /*
  84 ** Check to see if column iCol of index pIdx references any of the
  85 ** columns defined by aXRef and chngRowid.  Return true if it does
  86 ** and false if not.  This is an optimization.  False-positives are a
  87 ** performance degradation, but false-negatives can result in a corrupt
  88 ** index and incorrect answers.
  89 **
  90 ** aXRef[j] will be non-negative if column j of the original table is
  91 ** being updated.  chngRowid will be true if the rowid of the table is
  92 ** being updated.
  93 */
  94 static int indexColumnIsBeingUpdated(
  95   Index *pIdx,      /* The index to check */
  96   int iCol,         /* Which column of the index to check */
  97   int *aXRef,       /* aXRef[j]>=0 if column j is being updated */
  98   int chngRowid     /* true if the rowid is being updated */
  99 ){
 100   i16 iIdxCol = pIdx->aiColumn[iCol];
 101   assert( iIdxCol!=XN_ROWID ); /* Cannot index rowid */
 102   if( iIdxCol>=0 ){
 103     return aXRef[iIdxCol]>=0;
 104   }
 105   assert( iIdxCol==XN_EXPR );
 106   assert( pIdx->aColExpr!=0 );
 107   assert( pIdx->aColExpr->a[iCol].pExpr!=0 );
 108   return sqlite3ExprReferencesUpdatedColumn(pIdx->aColExpr->a[iCol].pExpr,
 109                                             aXRef,chngRowid);
 110 }
 111
 112 /*
 113 ** Check to see if index pIdx is a partial index whose conditional
 114 ** expression might change values due to an UPDATE.  Return true if
 115 ** the index is subject to change and false if the index is guaranteed
 116 ** to be unchanged.  This is an optimization.  False-positives are a
 117 ** performance degradation, but false-negatives can result in a corrupt
 118 ** index and incorrect answers.
 119 **
 120 ** aXRef[j] will be non-negative if column j of the original table is
 121 ** being updated.  chngRowid will be true if the rowid of the table is
 122 ** being updated.
 123 */
 124 static int indexWhereClauseMightChange(
 125   Index *pIdx,      /* The index to check */
 126   int *aXRef,       /* aXRef[j]>=0 if column j is being updated */
 127   int chngRowid     /* true if the rowid is being updated */
 128 ){
 129   if( pIdx->pPartIdxWhere==0 ) return 0;
 130   return sqlite3ExprReferencesUpdatedColumn(pIdx->pPartIdxWhere,
 131                                             aXRef, chngRowid);
 132 }
 133
 134 /*
 135 ** Allocate and return a pointer to an expression of type TK_ROW with
 136 ** Expr.iColumn set to value (iCol+1). The resolver will modify the
 137 ** expression to be a TK_COLUMN reading column iCol of the first
 138 ** table in the source-list (pSrc->a[0]).
 139 */
 140 static Expr *exprRowColumn(Parse *pParse, int iCol){
 141   Expr *pRet = sqlite3PExpr(pParse, TK_ROW, 0, 0);
 142   if( pRet ) pRet->iColumn = iCol+1;
 143   return pRet;
 144 }
 145
 146 /*
 147 ** Assuming both the pLimit and pOrderBy parameters are NULL, this function
 148 ** generates VM code to run the query:
 149 **
 150 **   SELECT <other-columns>, pChanges FROM pTabList WHERE pWhere
 151 **
 152 ** and write the results to the ephemeral table already opened as cursor
 153 ** iEph. None of pChanges, pTabList or pWhere are modified or consumed by
 154 ** this function, they must be deleted by the caller.
 155 **
 156 ** Or, if pLimit and pOrderBy are not NULL, and pTab is not a view:
 157 **
 158 **   SELECT <other-columns>, pChanges FROM pTabList
 159 **   WHERE pWhere
 160 **   GROUP BY <other-columns>
 161 **   ORDER BY pOrderBy LIMIT pLimit
 162 **
 163 ** If pTab is a view, the GROUP BY clause is omitted.
 164 **
 165 ** Exactly how results are written to table iEph, and exactly what
 166 ** the <other-columns> in the query above are is determined by the type
 167 ** of table pTabList->a[0].pTab.
 168 **
 169 ** If the table is a WITHOUT ROWID table, then argument pPk must be its
 170 ** PRIMARY KEY. In this case <other-columns> are the primary key columns
 171 ** of the table, in order. The results of the query are written to ephemeral
 172 ** table iEph as index keys, using OP_IdxInsert.
 173 **
 174 ** If the table is actually a view, then <other-columns> are all columns of
 175 ** the view. The results are written to the ephemeral table iEph as records
 176 ** with automatically assigned integer keys.
 177 **
 178 ** If the table is a virtual or ordinary intkey table, then <other-columns>
 179 ** is its rowid. For a virtual table, the results are written to iEph as
 180 ** records with automatically assigned integer keys For intkey tables, the
 181 ** rowid value in <other-columns> is used as the integer key, and the
 182 ** remaining fields make up the table record.
 183 */
 184 static void updateFromSelect(
 185   Parse *pParse,                  /* Parse context */
 186   int iEph,                       /* Cursor for open eph. table */
 187   Index *pPk,                     /* PK if table 0 is WITHOUT ROWID */
 188   ExprList *pChanges,             /* List of expressions to return */
 189   SrcList *pTabList,              /* List of tables to select from */
 190   Expr *pWhere,                   /* WHERE clause for query */
 191   ExprList *pOrderBy,             /* ORDER BY clause */
 192   Expr *pLimit                    /* LIMIT clause */
 193 ){
 194   int i;
 195   SelectDest dest;
 196   Select *pSelect = 0;
 197   ExprList *pList = 0;
 198   ExprList *pGrp = 0;
 199   Expr *pLimit2 = 0;
 200   ExprList *pOrderBy2 = 0;
 201   sqlite3 *db = pParse->db;
 202   Table *pTab = pTabList->a[0].pTab;
 203   SrcList *pSrc;
 204   Expr *pWhere2;
 205   int eDest;
 206
 207 #ifdef SQLITE_ENABLE_UPDATE_DELETE_LIMIT
 208   if( pOrderBy && pLimit==0 ) {
 209     sqlite3ErrorMsg(pParse, "ORDER BY without LIMIT on UPDATE");
 210     return;
 211   }
 212   pOrderBy2 = sqlite3ExprListDup(db, pOrderBy, 0);
 213   pLimit2 = sqlite3ExprDup(db, pLimit, 0);
 214 #else
 215   UNUSED_PARAMETER(pOrderBy);
 216   UNUSED_PARAMETER(pLimit);
 217 #endif
 218
 219   pSrc = sqlite3SrcListDup(db, pTabList, 0);
 220   pWhere2 = sqlite3ExprDup(db, pWhere, 0);
 221
 222   assert( pTabList->nSrc>1 );
 223   if( pSrc ){
 224     pSrc->a[0].fg.notCte = 1;
 225     pSrc->a[0].iCursor = -1;
 226     pSrc->a[0].pTab->nTabRef--;
 227     pSrc->a[0].pTab = 0;
 228   }
 229   if( pPk ){
 230     for(i=0; i<pPk->nKeyCol; i++){
 231       Expr *pNew = exprRowColumn(pParse, pPk->aiColumn[i]);
 232 #ifdef SQLITE_ENABLE_UPDATE_DELETE_LIMIT
 233       if( pLimit ){
 234         pGrp = sqlite3ExprListAppend(pParse, pGrp, sqlite3ExprDup(db, pNew, 0));
 235       }
 236 #endif
 237       pList = sqlite3ExprListAppend(pParse, pList, pNew);
 238     }
 239     eDest = IsVirtual(pTab) ? SRT_Table : SRT_Upfrom;
 240   }else if( IsView(pTab) ){
 241     for(i=0; i<pTab->nCol; i++){
 242       pList = sqlite3ExprListAppend(pParse, pList, exprRowColumn(pParse, i));
 243     }
 244     eDest = SRT_Table;
 245   }else{
 246     eDest = IsVirtual(pTab) ? SRT_Table : SRT_Upfrom;
 247     pList = sqlite3ExprListAppend(pParse, 0, sqlite3PExpr(pParse,TK_ROW,0,0));
 248 #ifdef SQLITE_ENABLE_UPDATE_DELETE_LIMIT
 249     if( pLimit ){
 250       pGrp = sqlite3ExprListAppend(pParse, 0, sqlite3PExpr(pParse,TK_ROW,0,0));
 251     }
 252 #endif
 253   }
 254   assert( pChanges!=0 || pParse->db->mallocFailed );
 255   if( pChanges ){
 256     for(i=0; i<pChanges->nExpr; i++){
 257       pList = sqlite3ExprListAppend(pParse, pList,
 258           sqlite3ExprDup(db, pChanges->a[i].pExpr, 0)
 259       );
 260     }
 261   }
 262   pSelect = sqlite3SelectNew(pParse, pList,
 263       pSrc, pWhere2, pGrp, 0, pOrderBy2, SF_UFSrcCheck|SF_IncludeHidden, pLimit2
 264   );
 265   if( pSelect ) pSelect->selFlags |= SF_OrderByReqd;
 266   sqlite3SelectDestInit(&dest, eDest, iEph);
 267   dest.iSDParm2 = (pPk ? pPk->nKeyCol : -1);
 268   sqlite3Select(pParse, pSelect, &dest);
 269   sqlite3SelectDelete(db, pSelect);
 270 }
 271
 272 /*
 273 ** Process an UPDATE statement.
 274 **
 275 **   UPDATE OR IGNORE tbl SET a=b, c=d FROM tbl2... WHERE e<5 AND f NOT NULL;
 276 **          \_______/ \_/     \______/      \_____/       \________________/
 277 **           onError   |      pChanges         |                pWhere
 278 **                     \_______________________/
 279 **                               pTabList
 280 */
 281 void sqlite3Update(
 282   Parse *pParse,         /* The parser context */
 283   SrcList *pTabList,     /* The table in which we should change things */
 284   ExprList *pChanges,    /* Things to be changed */
 285   Expr *pWhere,          /* The WHERE clause.  May be null */
 286   int onError,           /* How to handle constraint errors */
 287   ExprList *pOrderBy,    /* ORDER BY clause. May be null */
 288   Expr *pLimit,          /* LIMIT clause. May be null */
 289   Upsert *pUpsert        /* ON CONFLICT clause, or null */
 290 ){
 291   int i, j, k;           /* Loop counters */
 292   Table *pTab;           /* The table to be updated */
 293   int addrTop = 0;       /* VDBE instruction address of the start of the loop */
 294   WhereInfo *pWInfo = 0; /* Information about the WHERE clause */
 295   Vdbe *v;               /* The virtual database engine */
 296   Index *pIdx;           /* For looping over indices */
 297   Index *pPk;            /* The PRIMARY KEY index for WITHOUT ROWID tables */
 298   int nIdx;              /* Number of indices that need updating */
 299   int nAllIdx;           /* Total number of indexes */
 300   int iBaseCur;          /* Base cursor number */
 301   int iDataCur;          /* Cursor for the canonical data btree */
 302   int iIdxCur;           /* Cursor for the first index */
 303   sqlite3 *db;           /* The database structure */
 304   int *aRegIdx = 0;      /* Registers for to each index and the main table */
 305   int *aXRef = 0;        /* aXRef[i] is the index in pChanges->a[] of the
 306                          ** an expression for the i-th column of the table.
 307                          ** aXRef[i]==-1 if the i-th column is not changed. */
 308   u8 *aToOpen;           /* 1 for tables and indices to be opened */
 309   u8 chngPk;             /* PRIMARY KEY changed in a WITHOUT ROWID table */
 310   u8 chngRowid;          /* Rowid changed in a normal table */
 311   u8 chngKey;            /* Either chngPk or chngRowid */
 312   Expr *pRowidExpr = 0;  /* Expression defining the new record number */
 313   int iRowidExpr = -1;   /* Index of "rowid=" (or IPK) assignment in pChanges */
 314   AuthContext sContext;  /* The authorization context */
 315   NameContext sNC;       /* The name-context to resolve expressions in */
 316   int iDb;               /* Database containing the table being updated */
 317   int eOnePass;          /* ONEPASS_XXX value from where.c */
 318   int hasFK;             /* True if foreign key processing is required */
 319   int labelBreak;        /* Jump here to break out of UPDATE loop */
 320   int labelContinue;     /* Jump here to continue next step of UPDATE loop */
 321   int flags;             /* Flags for sqlite3WhereBegin() */
 322
 323 #ifndef SQLITE_OMIT_TRIGGER
 324   int isView;            /* True when updating a view (INSTEAD OF trigger) */
 325   Trigger *pTrigger;     /* List of triggers on pTab, if required */
 326   int tmask;             /* Mask of TRIGGER_BEFORE|TRIGGER_AFTER */
 327 #endif
 328   int newmask;           /* Mask of NEW.* columns accessed by BEFORE triggers */
 329   int iEph = 0;          /* Ephemeral table holding all primary key values */
 330   int nKey = 0;          /* Number of elements in regKey for WITHOUT ROWID */
 331   int aiCurOnePass[2];   /* The write cursors opened by WHERE_ONEPASS */
 332   int addrOpen = 0;      /* Address of OP_OpenEphemeral */
 333   int iPk = 0;           /* First of nPk cells holding PRIMARY KEY value */
 334   i16 nPk = 0;           /* Number of components of the PRIMARY KEY */
 335   int bReplace = 0;      /* True if REPLACE conflict resolution might happen */
 336   int bFinishSeek = 1;   /* The OP_FinishSeek opcode is needed */
 337   int nChangeFrom = 0;   /* If there is a FROM, pChanges->nExpr, else 0 */
 338
 339   /* Register Allocations */
 340   int regRowCount = 0;   /* A count of rows changed */
 341   int regOldRowid = 0;   /* The old rowid */
 342   int regNewRowid = 0;   /* The new rowid */
 343   int regNew = 0;        /* Content of the NEW.* table in triggers */
 344   int regOld = 0;        /* Content of OLD.* table in triggers */
 345   int regRowSet = 0;     /* Rowset of rows to be updated */
 346   int regKey = 0;        /* composite PRIMARY KEY value */
 347
 348   memset(&sContext, 0, sizeof(sContext));
 349   db = pParse->db;
 350   if( pParse->nErr || db->mallocFailed ){
 351     goto update_cleanup;
 352   }
 353
 354   /* Locate the table which we want to update.
 355   */
 356   pTab = sqlite3SrcListLookup(pParse, pTabList);
 357   if( pTab==0 ) goto update_cleanup;
 358   iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);
 359
 360   /* Figure out if we have any triggers and if the table being
 361   ** updated is a view.
 362   */
 363 #ifndef SQLITE_OMIT_TRIGGER
 364   pTrigger = sqlite3TriggersExist(pParse, pTab, TK_UPDATE, pChanges, &tmask);
 365   isView = IsView(pTab);
 366   assert( pTrigger || tmask==0 );
 367 #else
 368 # define pTrigger 0
 369 # define isView 0
 370 # define tmask 0
 371 #endif
 372 #ifdef SQLITE_OMIT_VIEW
 373 # undef isView
 374 # define isView 0
 375 #endif
 376
 377   /* If there was a FROM clause, set nChangeFrom to the number of expressions
 378   ** in the change-list. Otherwise, set it to 0. There cannot be a FROM
 379   ** clause if this function is being called to generate code for part of
 380   ** an UPSERT statement.  */
 381   nChangeFrom = (pTabList->nSrc>1) ? pChanges->nExpr : 0;
 382   assert( nChangeFrom==0 || pUpsert==0 );
 383
 384 #ifdef SQLITE_ENABLE_UPDATE_DELETE_LIMIT
 385   if( !isView && nChangeFrom==0 ){
 386     pWhere = sqlite3LimitWhere(
 387         pParse, pTabList, pWhere, pOrderBy, pLimit, "UPDATE"
 388     );
 389     pOrderBy = 0;
 390     pLimit = 0;
 391   }
 392 #endif
 393
 394   if( sqlite3ViewGetColumnNames(pParse, pTab) ){
 395     goto update_cleanup;
 396   }
 397   if( sqlite3IsReadOnly(pParse, pTab, tmask) ){
 398     goto update_cleanup;
 399   }
 400
 401   /* Allocate a cursors for the main database table and for all indices.
 402   ** The index cursors might not be used, but if they are used they
 403   ** need to occur right after the database cursor.  So go ahead and
 404   ** allocate enough space, just in case.
 405   */
 406   iBaseCur = iDataCur = pParse->nTab++;
 407   iIdxCur = iDataCur+1;
 408   pPk = HasRowid(pTab) ? 0 : sqlite3PrimaryKeyIndex(pTab);
 409   testcase( pPk!=0 && pPk!=pTab->pIndex );
 410   for(nIdx=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, nIdx++){
 411     if( pPk==pIdx ){
 412       iDataCur = pParse->nTab;
 413     }
 414     pParse->nTab++;
 415   }
 416   if( pUpsert ){
 417     /* On an UPSERT, reuse the same cursors already opened by INSERT */
 418     iDataCur = pUpsert->iDataCur;
 419     iIdxCur = pUpsert->iIdxCur;
 420     pParse->nTab = iBaseCur;
 421   }
 422   pTabList->a[0].iCursor = iDataCur;
 423
 424   /* Allocate space for aXRef[], aRegIdx[], and aToOpen[].
 425   ** Initialize aXRef[] and aToOpen[] to their default values.
 426   */
 427   aXRef = sqlite3DbMallocRawNN(db, sizeof(int) * (pTab->nCol+nIdx+1) + nIdx+2 );
 428   if( aXRef==0 ) goto update_cleanup;
 429   aRegIdx = aXRef+pTab->nCol;
 430   aToOpen = (u8*)(aRegIdx+nIdx+1);
 431   memset(aToOpen, 1, nIdx+1);
 432   aToOpen[nIdx+1] = 0;
 433   for(i=0; i<pTab->nCol; i++) aXRef[i] = -1;
 434
 435   /* Initialize the name-context */
 436   memset(&sNC, 0, sizeof(sNC));
 437   sNC.pParse = pParse;
 438   sNC.pSrcList = pTabList;
 439   sNC.uNC.pUpsert = pUpsert;
 440   sNC.ncFlags = NC_UUpsert;
 441
 442   /* Begin generating code. */
 443   v = sqlite3GetVdbe(pParse);
 444   if( v==0 ) goto update_cleanup;
 445
 446   /* Resolve the column names in all the expressions of the
 447   ** of the UPDATE statement.  Also find the column index
 448   ** for each column to be updated in the pChanges array.  For each
 449   ** column to be updated, make sure we have authorization to change
 450   ** that column.
 451   */
 452   chngRowid = chngPk = 0;
 453   for(i=0; i<pChanges->nExpr; i++){
 454     u8 hCol = sqlite3StrIHash(pChanges->a[i].zEName);
 455     /* If this is an UPDATE with a FROM clause, do not resolve expressions
 456     ** here. The call to sqlite3Select() below will do that. */
 457     if( nChangeFrom==0 && sqlite3ResolveExprNames(&sNC, pChanges->a[i].pExpr) ){
 458       goto update_cleanup;
 459     }
 460     for(j=0; j<pTab->nCol; j++){
 461       if( pTab->aCol[j].hName==hCol
 462        && sqlite3StrICmp(pTab->aCol[j].zCnName, pChanges->a[i].zEName)==0
 463       ){
 464         if( j==pTab->iPKey ){
 465           chngRowid = 1;
 466           pRowidExpr = pChanges->a[i].pExpr;
 467           iRowidExpr = i;
 468         }else if( pPk && (pTab->aCol[j].colFlags & COLFLAG_PRIMKEY)!=0 ){
 469           chngPk = 1;
 470         }
 471 #ifndef SQLITE_OMIT_GENERATED_COLUMNS
 472         else if( pTab->aCol[j].colFlags & COLFLAG_GENERATED ){
 473           testcase( pTab->aCol[j].colFlags & COLFLAG_VIRTUAL );
 474           testcase( pTab->aCol[j].colFlags & COLFLAG_STORED );
 475           sqlite3ErrorMsg(pParse,
 476              "cannot UPDATE generated column \"%s\"",
 477              pTab->aCol[j].zCnName);
 478           goto update_cleanup;
 479         }
 480 #endif
 481         aXRef[j] = i;
 482         break;
 483       }
 484     }
 485     if( j>=pTab->nCol ){
 486       if( pPk==0 && sqlite3IsRowid(pChanges->a[i].zEName) ){
 487         j = -1;
 488         chngRowid = 1;
 489         pRowidExpr = pChanges->a[i].pExpr;
 490         iRowidExpr = i;
 491       }else{
 492         sqlite3ErrorMsg(pParse, "no such column: %s", pChanges->a[i].zEName);
 493         pParse->checkSchema = 1;
 494         goto update_cleanup;
 495       }
 496     }
 497 #ifndef SQLITE_OMIT_AUTHORIZATION
 498     {
 499       int rc;
 500       rc = sqlite3AuthCheck(pParse, SQLITE_UPDATE, pTab->zName,
 501                             j<0 ? "ROWID" : pTab->aCol[j].zCnName,
 502                             db->aDb[iDb].zDbSName);
 503       if( rc==SQLITE_DENY ){
 504         goto update_cleanup;
 505       }else if( rc==SQLITE_IGNORE ){
 506         aXRef[j] = -1;
 507       }
 508     }
 509 #endif
 510   }
 511   assert( (chngRowid & chngPk)==0 );
 512   assert( chngRowid==0 || chngRowid==1 );
 513   assert( chngPk==0 || chngPk==1 );
 514   chngKey = chngRowid + chngPk;
 515
 516 #ifndef SQLITE_OMIT_GENERATED_COLUMNS
 517   /* Mark generated columns as changing if their generator expressions
 518   ** reference any changing column.  The actual aXRef[] value for
 519   ** generated expressions is not used, other than to check to see that it
 520   ** is non-negative, so the value of aXRef[] for generated columns can be
 521   ** set to any non-negative number.  We use 99999 so that the value is
 522   ** obvious when looking at aXRef[] in a symbolic debugger.
 523   */
 524   if( pTab->tabFlags & TF_HasGenerated ){
 525     int bProgress;
 526     testcase( pTab->tabFlags & TF_HasVirtual );
 527     testcase( pTab->tabFlags & TF_HasStored );
 528     do{
 529       bProgress = 0;
 530       for(i=0; i<pTab->nCol; i++){
 531         if( aXRef[i]>=0 ) continue;
 532         if( (pTab->aCol[i].colFlags & COLFLAG_GENERATED)==0 ) continue;
 533         if( sqlite3ExprReferencesUpdatedColumn(
 534                 sqlite3ColumnExpr(pTab, &pTab->aCol[i]),
 535                  aXRef, chngRowid)
 536         ){
 537           aXRef[i] = 99999;
 538           bProgress = 1;
 539         }
 540       }
 541     }while( bProgress );
 542   }
 543 #endif
 544
 545   /* The SET expressions are not actually used inside the WHERE loop.
 546   ** So reset the colUsed mask. Unless this is a virtual table. In that
 547   ** case, set all bits of the colUsed mask (to ensure that the virtual
 548   ** table implementation makes all columns available).
 549   */
 550   pTabList->a[0].colUsed = IsVirtual(pTab) ? ALLBITS : 0;
 551
 552   hasFK = sqlite3FkRequired(pParse, pTab, aXRef, chngKey);
 553
 554   /* There is one entry in the aRegIdx[] array for each index on the table
 555   ** being updated.  Fill in aRegIdx[] with a register number that will hold
 556   ** the key for accessing each index.
 557   */
 558   if( onError==OE_Replace ) bReplace = 1;
 559   for(nAllIdx=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, nAllIdx++){
 560     int reg;
 561     if( chngKey || hasFK>1 || pIdx==pPk
 562      || indexWhereClauseMightChange(pIdx,aXRef,chngRowid)
 563     ){
 564       reg = ++pParse->nMem;
 565       pParse->nMem += pIdx->nColumn;
 566     }else{
 567       reg = 0;
 568       for(i=0; i<pIdx->nKeyCol; i++){
 569         if( indexColumnIsBeingUpdated(pIdx, i, aXRef, chngRowid) ){
 570           reg = ++pParse->nMem;
 571           pParse->nMem += pIdx->nColumn;
 572           if( onError==OE_Default && pIdx->onError==OE_Replace ){
 573             bReplace = 1;
 574           }
 575           break;
 576         }
 577       }
 578     }
 579     if( reg==0 ) aToOpen[nAllIdx+1] = 0;
 580     aRegIdx[nAllIdx] = reg;
 581   }
 582   aRegIdx[nAllIdx] = ++pParse->nMem;  /* Register storing the table record */
 583   if( bReplace ){
 584     /* If REPLACE conflict resolution might be invoked, open cursors on all
 585     ** indexes in case they are needed to delete records.  */
 586     memset(aToOpen, 1, nIdx+1);
 587   }
 588
 589   if( pParse->nested==0 ) sqlite3VdbeCountChanges(v);
 590   sqlite3BeginWriteOperation(pParse, pTrigger || hasFK, iDb);
 591
 592   /* Allocate required registers. */
 593   if( !IsVirtual(pTab) ){
 594     /* For now, regRowSet and aRegIdx[nAllIdx] share the same register.
 595     ** If regRowSet turns out to be needed, then aRegIdx[nAllIdx] will be
 596     ** reallocated.  aRegIdx[nAllIdx] is the register in which the main
 597     ** table record is written.  regRowSet holds the RowSet for the
 598     ** two-pass update algorithm. */
 599     assert( aRegIdx[nAllIdx]==pParse->nMem );
 600     regRowSet = aRegIdx[nAllIdx];
 601     regOldRowid = regNewRowid = ++pParse->nMem;
 602     if( chngPk || pTrigger || hasFK ){
 603       regOld = pParse->nMem + 1;
 604       pParse->nMem += pTab->nCol;
 605     }
 606     if( chngKey || pTrigger || hasFK ){
 607       regNewRowid = ++pParse->nMem;
 608     }
 609     regNew = pParse->nMem + 1;
 610     pParse->nMem += pTab->nCol;
 611   }
 612
 613   /* Start the view context. */
 614   if( isView ){
 615     sqlite3AuthContextPush(pParse, &sContext, pTab->zName);
 616   }
 617
 618   /* If we are trying to update a view, realize that view into
 619   ** an ephemeral table.
 620   */
 621 #if !defined(SQLITE_OMIT_VIEW) && !defined(SQLITE_OMIT_TRIGGER)
 622   if( nChangeFrom==0 && isView ){
 623     sqlite3MaterializeView(pParse, pTab,
 624         pWhere, pOrderBy, pLimit, iDataCur
 625     );
 626     pOrderBy = 0;
 627     pLimit = 0;
 628   }
 629 #endif
 630
 631   /* Resolve the column names in all the expressions in the
 632   ** WHERE clause.
 633   */
 634   if( nChangeFrom==0 && sqlite3ResolveExprNames(&sNC, pWhere) ){
 635     goto update_cleanup;
 636   }
 637
 638 #ifndef SQLITE_OMIT_VIRTUALTABLE
 639   /* Virtual tables must be handled separately */
 640   if( IsVirtual(pTab) ){
 641     updateVirtualTable(pParse, pTabList, pTab, pChanges, pRowidExpr, aXRef,
 642                        pWhere, onError);
 643     goto update_cleanup;
 644   }
 645 #endif
 646
 647   /* Jump to labelBreak to abandon further processing of this UPDATE */
 648   labelContinue = labelBreak = sqlite3VdbeMakeLabel(pParse);
 649
 650   /* Not an UPSERT.  Normal processing.  Begin by
 651   ** initialize the count of updated rows */
 652   if( (db->flags&SQLITE_CountRows)!=0
 653    && !pParse->pTriggerTab
 654    && !pParse->nested
 655    && !pParse->bReturning
 656    && pUpsert==0
 657   ){
 658     regRowCount = ++pParse->nMem;
 659     sqlite3VdbeAddOp2(v, OP_Integer, 0, regRowCount);
 660   }
 661
 662   if( nChangeFrom==0 && HasRowid(pTab) ){
 663     sqlite3VdbeAddOp3(v, OP_Null, 0, regRowSet, regOldRowid);
 664     iEph = pParse->nTab++;
 665     addrOpen = sqlite3VdbeAddOp3(v, OP_OpenEphemeral, iEph, 0, regRowSet);
 666   }else{
 667     assert( pPk!=0 || HasRowid(pTab) );
 668     nPk = pPk ? pPk->nKeyCol : 0;
 669     iPk = pParse->nMem+1;
 670     pParse->nMem += nPk;
 671     pParse->nMem += nChangeFrom;
 672     regKey = ++pParse->nMem;
 673     if( pUpsert==0 ){
 674       int nEphCol = nPk + nChangeFrom + (isView ? pTab->nCol : 0);
 675       iEph = pParse->nTab++;
 676       if( pPk ) sqlite3VdbeAddOp3(v, OP_Null, 0, iPk, iPk+nPk-1);
 677       addrOpen = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, iEph, nEphCol);
 678       if( pPk ){
 679         KeyInfo *pKeyInfo = sqlite3KeyInfoOfIndex(pParse, pPk);
 680         if( pKeyInfo ){
 681           pKeyInfo->nAllField = nEphCol;
 682           sqlite3VdbeAppendP4(v, pKeyInfo, P4_KEYINFO);
 683         }
 684       }
 685       if( nChangeFrom ){
 686         updateFromSelect(
 687             pParse, iEph, pPk, pChanges, pTabList, pWhere, pOrderBy, pLimit
 688         );
 689 #ifndef SQLITE_OMIT_SUBQUERY
 690         if( isView ) iDataCur = iEph;
 691 #endif
 692       }
 693     }
 694   }
 695
 696   if( nChangeFrom ){
 697     sqlite3MultiWrite(pParse);
 698     eOnePass = ONEPASS_OFF;
 699     nKey = nPk;
 700     regKey = iPk;
 701   }else{
 702     if( pUpsert ){
 703       /* If this is an UPSERT, then all cursors have already been opened by
 704       ** the outer INSERT and the data cursor should be pointing at the row
 705       ** that is to be updated.  So bypass the code that searches for the
 706       ** row(s) to be updated.
 707       */
 708       pWInfo = 0;
 709       eOnePass = ONEPASS_SINGLE;
 710       sqlite3ExprIfFalse(pParse, pWhere, labelBreak, SQLITE_JUMPIFNULL);
 711       bFinishSeek = 0;
 712     }else{
 713       /* Begin the database scan.
 714       **
 715       ** Do not consider a single-pass strategy for a multi-row update if
 716       ** there are any triggers or foreign keys to process, or rows may
 717       ** be deleted as a result of REPLACE conflict handling. Any of these
 718       ** things might disturb a cursor being used to scan through the table
 719       ** or index, causing a single-pass approach to malfunction.  */
 720       flags = WHERE_ONEPASS_DESIRED;
 721       if( !pParse->nested && !pTrigger && !hasFK && !chngKey && !bReplace ){
 722         flags |= WHERE_ONEPASS_MULTIROW;
 723       }
 724       pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, 0, 0, flags,iIdxCur);
 725       if( pWInfo==0 ) goto update_cleanup;
 726
 727       /* A one-pass strategy that might update more than one row may not
 728       ** be used if any column of the index used for the scan is being
 729       ** updated. Otherwise, if there is an index on "b", statements like
 730       ** the following could create an infinite loop:
 731       **
 732       **   UPDATE t1 SET b=b+1 WHERE b>?
 733       **
 734       ** Fall back to ONEPASS_OFF if where.c has selected a ONEPASS_MULTI
 735       ** strategy that uses an index for which one or more columns are being
 736       ** updated.  */
 737       eOnePass = sqlite3WhereOkOnePass(pWInfo, aiCurOnePass);
 738       bFinishSeek = sqlite3WhereUsesDeferredSeek(pWInfo);
 739       if( eOnePass!=ONEPASS_SINGLE ){
 740         sqlite3MultiWrite(pParse);
 741         if( eOnePass==ONEPASS_MULTI ){
 742           int iCur = aiCurOnePass[1];
 743           if( iCur>=0 && iCur!=iDataCur && aToOpen[iCur-iBaseCur] ){
 744             eOnePass = ONEPASS_OFF;
 745           }
 746           assert( iCur!=iDataCur || !HasRowid(pTab) );
 747         }
 748       }
 749     }
 750
 751     if( HasRowid(pTab) ){
 752       /* Read the rowid of the current row of the WHERE scan. In ONEPASS_OFF
 753       ** mode, write the rowid into the FIFO. In either of the one-pass modes,
 754       ** leave it in register regOldRowid.  */
 755       sqlite3VdbeAddOp2(v, OP_Rowid, iDataCur, regOldRowid);
 756       if( eOnePass==ONEPASS_OFF ){
 757         aRegIdx[nAllIdx] = ++pParse->nMem;
 758         sqlite3VdbeAddOp3(v, OP_Insert, iEph, regRowSet, regOldRowid);
 759       }else{
 760         if( ALWAYS(addrOpen) ) sqlite3VdbeChangeToNoop(v, addrOpen);
 761       }
 762     }else{
 763       /* Read the PK of the current row into an array of registers. In
 764       ** ONEPASS_OFF mode, serialize the array into a record and store it in
 765       ** the ephemeral table. Or, in ONEPASS_SINGLE or MULTI mode, change
 766       ** the OP_OpenEphemeral instruction to a Noop (the ephemeral table
 767       ** is not required) and leave the PK fields in the array of registers.  */
 768       for(i=0; i<nPk; i++){
 769         assert( pPk->aiColumn[i]>=0 );
 770         sqlite3ExprCodeGetColumnOfTable(v, pTab, iDataCur,
 771                                         pPk->aiColumn[i], iPk+i);
 772       }
 773       if( eOnePass ){
 774         if( addrOpen ) sqlite3VdbeChangeToNoop(v, addrOpen);
 775         nKey = nPk;
 776         regKey = iPk;
 777       }else{
 778         sqlite3VdbeAddOp4(v, OP_MakeRecord, iPk, nPk, regKey,
 779                           sqlite3IndexAffinityStr(db, pPk), nPk);
 780         sqlite3VdbeAddOp4Int(v, OP_IdxInsert, iEph, regKey, iPk, nPk);
 781       }
 782     }
 783   }
 784
 785   if( pUpsert==0 ){
 786     if( nChangeFrom==0 && eOnePass!=ONEPASS_MULTI ){
 787       sqlite3WhereEnd(pWInfo);
 788     }
 789
 790     if( !isView ){
 791       int addrOnce = 0;
 792
 793       /* Open every index that needs updating. */
 794       if( eOnePass!=ONEPASS_OFF ){
 795         if( aiCurOnePass[0]>=0 ) aToOpen[aiCurOnePass[0]-iBaseCur] = 0;
 796         if( aiCurOnePass[1]>=0 ) aToOpen[aiCurOnePass[1]-iBaseCur] = 0;
 797       }
 798
 799       if( eOnePass==ONEPASS_MULTI && (nIdx-(aiCurOnePass[1]>=0))>0 ){
 800         addrOnce = sqlite3VdbeAddOp0(v, OP_Once); VdbeCoverage(v);
 801       }
 802       sqlite3OpenTableAndIndices(pParse, pTab, OP_OpenWrite, 0, iBaseCur,
 803                                  aToOpen, 0, 0);
 804       if( addrOnce ){
 805         sqlite3VdbeJumpHereOrPopInst(v, addrOnce);
 806       }
 807     }
 808
 809     /* Top of the update loop */
 810     if( eOnePass!=ONEPASS_OFF ){
 811       if( aiCurOnePass[0]!=iDataCur
 812        && aiCurOnePass[1]!=iDataCur
 813 #ifdef SQLITE_ALLOW_ROWID_IN_VIEW
 814        && !isView
 815 #endif
 816       ){
 817         assert( pPk );
 818         sqlite3VdbeAddOp4Int(v, OP_NotFound, iDataCur, labelBreak, regKey,nKey);
 819         VdbeCoverage(v);
 820       }
 821       if( eOnePass!=ONEPASS_SINGLE ){
 822         labelContinue = sqlite3VdbeMakeLabel(pParse);
 823       }
 824       sqlite3VdbeAddOp2(v, OP_IsNull, pPk ? regKey : regOldRowid, labelBreak);
 825       VdbeCoverageIf(v, pPk==0);
 826       VdbeCoverageIf(v, pPk!=0);
 827     }else if( pPk || nChangeFrom ){
 828       labelContinue = sqlite3VdbeMakeLabel(pParse);
 829       sqlite3VdbeAddOp2(v, OP_Rewind, iEph, labelBreak); VdbeCoverage(v);
 830       addrTop = sqlite3VdbeCurrentAddr(v);
 831       if( nChangeFrom ){
 832         if( !isView ){
 833           if( pPk ){
 834             for(i=0; i<nPk; i++){
 835               sqlite3VdbeAddOp3(v, OP_Column, iEph, i, iPk+i);
 836             }
 837             sqlite3VdbeAddOp4Int(
 838                 v, OP_NotFound, iDataCur, labelContinue, iPk, nPk
 839             ); VdbeCoverage(v);
 840           }else{
 841             sqlite3VdbeAddOp2(v, OP_Rowid, iEph, regOldRowid);
 842             sqlite3VdbeAddOp3(
 843                 v, OP_NotExists, iDataCur, labelContinue, regOldRowid
 844             ); VdbeCoverage(v);
 845           }
 846         }
 847       }else{
 848         sqlite3VdbeAddOp2(v, OP_RowData, iEph, regKey);
 849         sqlite3VdbeAddOp4Int(v, OP_NotFound, iDataCur, labelContinue, regKey,0);
 850         VdbeCoverage(v);
 851       }
 852     }else{
 853       sqlite3VdbeAddOp2(v, OP_Rewind, iEph, labelBreak); VdbeCoverage(v);
 854       labelContinue = sqlite3VdbeMakeLabel(pParse);
 855       addrTop = sqlite3VdbeAddOp2(v, OP_Rowid, iEph, regOldRowid);
 856       VdbeCoverage(v);
 857       sqlite3VdbeAddOp3(v, OP_NotExists, iDataCur, labelContinue, regOldRowid);
 858       VdbeCoverage(v);
 859     }
 860   }
 861
 862   /* If the rowid value will change, set register regNewRowid to
 863   ** contain the new value. If the rowid is not being modified,
 864   ** then regNewRowid is the same register as regOldRowid, which is
 865   ** already populated.  */
 866   assert( chngKey || pTrigger || hasFK || regOldRowid==regNewRowid );
 867   if( chngRowid ){
 868     assert( iRowidExpr>=0 );
 869     if( nChangeFrom==0 ){
 870       sqlite3ExprCode(pParse, pRowidExpr, regNewRowid);
 871     }else{
 872       sqlite3VdbeAddOp3(v, OP_Column, iEph, iRowidExpr, regNewRowid);
 873     }
 874     sqlite3VdbeAddOp1(v, OP_MustBeInt, regNewRowid); VdbeCoverage(v);
 875   }
 876
 877   /* Compute the old pre-UPDATE content of the row being changed, if that
 878   ** information is needed */
 879   if( chngPk || hasFK || pTrigger ){
 880     u32 oldmask = (hasFK ? sqlite3FkOldmask(pParse, pTab) : 0);
 881     oldmask |= sqlite3TriggerColmask(pParse,
 882         pTrigger, pChanges, 0, TRIGGER_BEFORE|TRIGGER_AFTER, pTab, onError
 883     );
 884     for(i=0; i<pTab->nCol; i++){
 885       u32 colFlags = pTab->aCol[i].colFlags;
 886       k = sqlite3TableColumnToStorage(pTab, i) + regOld;
 887       if( oldmask==0xffffffff
 888        || (i<32 && (oldmask & MASKBIT32(i))!=0)
 889        || (colFlags & COLFLAG_PRIMKEY)!=0
 890       ){
 891         testcase(  oldmask!=0xffffffff && i==31 );
 892         sqlite3ExprCodeGetColumnOfTable(v, pTab, iDataCur, i, k);
 893       }else{
 894         sqlite3VdbeAddOp2(v, OP_Null, 0, k);
 895       }
 896     }
 897     if( chngRowid==0 && pPk==0 ){
 898       sqlite3VdbeAddOp2(v, OP_Copy, regOldRowid, regNewRowid);
 899     }
 900   }
 901
 902   /* Populate the array of registers beginning at regNew with the new
 903   ** row data. This array is used to check constants, create the new
 904   ** table and index records, and as the values for any new.* references
 905   ** made by triggers.
 906   **
 907   ** If there are one or more BEFORE triggers, then do not populate the
 908   ** registers associated with columns that are (a) not modified by
 909   ** this UPDATE statement and (b) not accessed by new.* references. The
 910   ** values for registers not modified by the UPDATE must be reloaded from
 911   ** the database after the BEFORE triggers are fired anyway (as the trigger
 912   ** may have modified them). So not loading those that are not going to
 913   ** be used eliminates some redundant opcodes.
 914   */
 915   newmask = sqlite3TriggerColmask(
 916       pParse, pTrigger, pChanges, 1, TRIGGER_BEFORE, pTab, onError
 917   );
 918   for(i=0, k=regNew; i<pTab->nCol; i++, k++){
 919     if( i==pTab->iPKey ){
 920       sqlite3VdbeAddOp2(v, OP_Null, 0, k);
 921     }else if( (pTab->aCol[i].colFlags & COLFLAG_GENERATED)!=0 ){
 922       if( pTab->aCol[i].colFlags & COLFLAG_VIRTUAL ) k--;
 923     }else{
 924       j = aXRef[i];
 925       if( j>=0 ){
 926         if( nChangeFrom ){
 927           int nOff = (isView ? pTab->nCol : nPk);
 928           assert( eOnePass==ONEPASS_OFF );
 929           sqlite3VdbeAddOp3(v, OP_Column, iEph, nOff+j, k);
 930         }else{
 931           sqlite3ExprCode(pParse, pChanges->a[j].pExpr, k);
 932         }
 933       }else if( 0==(tmask&TRIGGER_BEFORE) || i>31 || (newmask & MASKBIT32(i)) ){
 934         /* This branch loads the value of a column that will not be changed
 935         ** into a register. This is done if there are no BEFORE triggers, or
 936         ** if there are one or more BEFORE triggers that use this value via
 937         ** a new.* reference in a trigger program.
 938         */
 939         testcase( i==31 );
 940         testcase( i==32 );
 941         sqlite3ExprCodeGetColumnOfTable(v, pTab, iDataCur, i, k);
 942         bFinishSeek = 0;
 943       }else{
 944         sqlite3VdbeAddOp2(v, OP_Null, 0, k);
 945       }
 946     }
 947   }
 948 #ifndef SQLITE_OMIT_GENERATED_COLUMNS
 949   if( pTab->tabFlags & TF_HasGenerated ){
 950     testcase( pTab->tabFlags & TF_HasVirtual );
 951     testcase( pTab->tabFlags & TF_HasStored );
 952     sqlite3ComputeGeneratedColumns(pParse, regNew, pTab);
 953   }
 954 #endif
 955
 956   /* Fire any BEFORE UPDATE triggers. This happens before constraints are
 957   ** verified. One could argue that this is wrong.
 958   */
 959   if( tmask&TRIGGER_BEFORE ){
 960     sqlite3TableAffinity(v, pTab, regNew);
 961     sqlite3CodeRowTrigger(pParse, pTrigger, TK_UPDATE, pChanges,
 962         TRIGGER_BEFORE, pTab, regOldRowid, onError, labelContinue);
 963
 964     if( !isView ){
 965       /* The row-trigger may have deleted the row being updated. In this
 966       ** case, jump to the next row. No updates or AFTER triggers are
 967       ** required. This behavior - what happens when the row being updated
 968       ** is deleted or renamed by a BEFORE trigger - is left undefined in the
 969       ** documentation.
 970       */
 971       if( pPk ){
 972         sqlite3VdbeAddOp4Int(v, OP_NotFound,iDataCur,labelContinue,regKey,nKey);
 973         VdbeCoverage(v);
 974       }else{
 975         sqlite3VdbeAddOp3(v, OP_NotExists, iDataCur, labelContinue,regOldRowid);
 976         VdbeCoverage(v);
 977       }
 978
 979       /* After-BEFORE-trigger-reload-loop:
 980       ** If it did not delete it, the BEFORE trigger may still have modified
 981       ** some of the columns of the row being updated. Load the values for
 982       ** all columns not modified by the update statement into their registers
 983       ** in case this has happened. Only unmodified columns are reloaded.
 984       ** The values computed for modified columns use the values before the
 985       ** BEFORE trigger runs.  See test case trigger1-18.0 (added 2018-04-26)
 986       ** for an example.
 987       */
 988       for(i=0, k=regNew; i<pTab->nCol; i++, k++){
 989         if( pTab->aCol[i].colFlags & COLFLAG_GENERATED ){
 990           if( pTab->aCol[i].colFlags & COLFLAG_VIRTUAL ) k--;
 991         }else if( aXRef[i]<0 && i!=pTab->iPKey ){
 992           sqlite3ExprCodeGetColumnOfTable(v, pTab, iDataCur, i, k);
 993         }
 994       }
 995 #ifndef SQLITE_OMIT_GENERATED_COLUMNS
 996       if( pTab->tabFlags & TF_HasGenerated ){
 997         testcase( pTab->tabFlags & TF_HasVirtual );
 998         testcase( pTab->tabFlags & TF_HasStored );
 999         sqlite3ComputeGeneratedColumns(pParse, regNew, pTab);
1000       }
1001 #endif
1002     }
1003   }
1004
1005   if( !isView ){
1006     /* Do constraint checks. */
1007     assert( regOldRowid>0 );
1008     sqlite3GenerateConstraintChecks(pParse, pTab, aRegIdx, iDataCur, iIdxCur,
1009         regNewRowid, regOldRowid, chngKey, onError, labelContinue, &bReplace,
1010         aXRef, 0);
1011
1012     /* If REPLACE conflict handling may have been used, or if the PK of the
1013     ** row is changing, then the GenerateConstraintChecks() above may have
1014     ** moved cursor iDataCur. Reseek it. */
1015     if( bReplace || chngKey ){
1016       if( pPk ){
1017         sqlite3VdbeAddOp4Int(v, OP_NotFound,iDataCur,labelContinue,regKey,nKey);
1018       }else{
1019         sqlite3VdbeAddOp3(v, OP_NotExists, iDataCur, labelContinue,regOldRowid);
1020       }
1021       VdbeCoverageNeverTaken(v);
1022     }
1023
1024     /* Do FK constraint checks. */
1025     if( hasFK ){
1026       sqlite3FkCheck(pParse, pTab, regOldRowid, 0, aXRef, chngKey);
1027     }
1028
1029     /* Delete the index entries associated with the current record.  */
1030     sqlite3GenerateRowIndexDelete(pParse, pTab, iDataCur, iIdxCur, aRegIdx, -1);
1031
1032     /* We must run the OP_FinishSeek opcode to resolve a prior
1033     ** OP_DeferredSeek if there is any possibility that there have been
1034     ** no OP_Column opcodes since the OP_DeferredSeek was issued.  But
1035     ** we want to avoid the OP_FinishSeek if possible, as running it
1036     ** costs CPU cycles. */
1037     if( bFinishSeek ){
1038       sqlite3VdbeAddOp1(v, OP_FinishSeek, iDataCur);
1039     }
1040
1041     /* If changing the rowid value, or if there are foreign key constraints
1042     ** to process, delete the old record. Otherwise, add a noop OP_Delete
1043     ** to invoke the pre-update hook.
1044     **
1045     ** That (regNew==regnewRowid+1) is true is also important for the
1046     ** pre-update hook. If the caller invokes preupdate_new(), the returned
1047     ** value is copied from memory cell (regNewRowid+1+iCol), where iCol
1048     ** is the column index supplied by the user.
1049     */
1050     assert( regNew==regNewRowid+1 );
1051 #ifdef SQLITE_ENABLE_PREUPDATE_HOOK
1052     sqlite3VdbeAddOp3(v, OP_Delete, iDataCur,
1053         OPFLAG_ISUPDATE | ((hasFK>1 || chngKey) ? 0 : OPFLAG_ISNOOP),
1054         regNewRowid
1055     );
1056     if( eOnePass==ONEPASS_MULTI ){
1057       assert( hasFK==0 && chngKey==0 );
1058       sqlite3VdbeChangeP5(v, OPFLAG_SAVEPOSITION);
1059     }
1060     if( !pParse->nested ){
1061       sqlite3VdbeAppendP4(v, pTab, P4_TABLE);
1062     }
1063 #else
1064     if( hasFK>1 || chngKey ){
1065       sqlite3VdbeAddOp2(v, OP_Delete, iDataCur, 0);
1066     }
1067 #endif
1068
1069     if( hasFK ){
1070       sqlite3FkCheck(pParse, pTab, 0, regNewRowid, aXRef, chngKey);
1071     }
1072
1073     /* Insert the new index entries and the new record. */
1074     sqlite3CompleteInsertion(
1075         pParse, pTab, iDataCur, iIdxCur, regNewRowid, aRegIdx,
1076         OPFLAG_ISUPDATE | (eOnePass==ONEPASS_MULTI ? OPFLAG_SAVEPOSITION : 0),
1077         0, 0
1078     );
1079
1080     /* Do any ON CASCADE, SET NULL or SET DEFAULT operations required to
1081     ** handle rows (possibly in other tables) that refer via a foreign key
1082     ** to the row just updated. */
1083     if( hasFK ){
1084       sqlite3FkActions(pParse, pTab, pChanges, regOldRowid, aXRef, chngKey);
1085     }
1086   }
1087
1088   /* Increment the row counter
1089   */
1090   if( regRowCount ){
1091     sqlite3VdbeAddOp2(v, OP_AddImm, regRowCount, 1);
1092   }
1093
1094   sqlite3CodeRowTrigger(pParse, pTrigger, TK_UPDATE, pChanges,
1095       TRIGGER_AFTER, pTab, regOldRowid, onError, labelContinue);
1096
1097   /* Repeat the above with the next record to be updated, until
1098   ** all record selected by the WHERE clause have been updated.
1099   */
1100   if( eOnePass==ONEPASS_SINGLE ){
1101     /* Nothing to do at end-of-loop for a single-pass */
1102   }else if( eOnePass==ONEPASS_MULTI ){
1103     sqlite3VdbeResolveLabel(v, labelContinue);
1104     sqlite3WhereEnd(pWInfo);
1105   }else{
1106     sqlite3VdbeResolveLabel(v, labelContinue);
1107     sqlite3VdbeAddOp2(v, OP_Next, iEph, addrTop); VdbeCoverage(v);
1108   }
1109   sqlite3VdbeResolveLabel(v, labelBreak);
1110
1111   /* Update the sqlite_sequence table by storing the content of the
1112   ** maximum rowid counter values recorded while inserting into
1113   ** autoincrement tables.
1114   */
1115   if( pParse->nested==0 && pParse->pTriggerTab==0 && pUpsert==0 ){
1116     sqlite3AutoincrementEnd(pParse);
1117   }
1118
1119   /*
1120   ** Return the number of rows that were changed, if we are tracking
1121   ** that information.
1122   */
1123   if( regRowCount ){
1124     sqlite3VdbeAddOp2(v, OP_ChngCntRow, regRowCount, 1);
1125     sqlite3VdbeSetNumCols(v, 1);
1126     sqlite3VdbeSetColName(v, 0, COLNAME_NAME, "rows updated", SQLITE_STATIC);
1127   }
1128
1129 update_cleanup:
1130   sqlite3AuthContextPop(&sContext);
1131   sqlite3DbFree(db, aXRef); /* Also frees aRegIdx[] and aToOpen[] */
1132   sqlite3SrcListDelete(db, pTabList);
1133   sqlite3ExprListDelete(db, pChanges);
1134   sqlite3ExprDelete(db, pWhere);
1135 #if defined(SQLITE_ENABLE_UPDATE_DELETE_LIMIT)
1136   sqlite3ExprListDelete(db, pOrderBy);
1137   sqlite3ExprDelete(db, pLimit);
1138 #endif
1139   return;
1140 }
1141 /* Make sure "isView" and other macros defined above are undefined. Otherwise
1142 ** they may interfere with compilation of other functions in this file
1143 ** (or in another file, if this file becomes part of the amalgamation).  */
1144 #ifdef isView
1145  #undef isView
1146 #endif
1147 #ifdef pTrigger
1148  #undef pTrigger
1149 #endif
1150
1151 #ifndef SQLITE_OMIT_VIRTUALTABLE
1152 /*
1153 ** Generate code for an UPDATE of a virtual table.
1154 **
1155 ** There are two possible strategies - the default and the special
1156 ** "onepass" strategy. Onepass is only used if the virtual table
1157 ** implementation indicates that pWhere may match at most one row.
1158 **
1159 ** The default strategy is to create an ephemeral table that contains
1160 ** for each row to be changed:
1161 **
1162 **   (A)  The original rowid of that row.
1163 **   (B)  The revised rowid for the row.
1164 **   (C)  The content of every column in the row.
1165 **
1166 ** Then loop through the contents of this ephemeral table executing a
1167 ** VUpdate for each row. When finished, drop the ephemeral table.
1168 **
1169 ** The "onepass" strategy does not use an ephemeral table. Instead, it
1170 ** stores the same values (A, B and C above) in a register array and
1171 ** makes a single invocation of VUpdate.
1172 */
1173 static void updateVirtualTable(
1174   Parse *pParse,       /* The parsing context */
1175   SrcList *pSrc,       /* The virtual table to be modified */
1176   Table *pTab,         /* The virtual table */
1177   ExprList *pChanges,  /* The columns to change in the UPDATE statement */
1178   Expr *pRowid,        /* Expression used to recompute the rowid */
1179   int *aXRef,          /* Mapping from columns of pTab to entries in pChanges */
1180   Expr *pWhere,        /* WHERE clause of the UPDATE statement */
1181   int onError          /* ON CONFLICT strategy */
1182 ){
1183   Vdbe *v = pParse->pVdbe;  /* Virtual machine under construction */
1184   int ephemTab;             /* Table holding the result of the SELECT */
1185   int i;                    /* Loop counter */
1186   sqlite3 *db = pParse->db; /* Database connection */
1187   const char *pVTab = (const char*)sqlite3GetVTable(db, pTab);
1188   WhereInfo *pWInfo = 0;
1189   int nArg = 2 + pTab->nCol;      /* Number of arguments to VUpdate */
1190   int regArg;                     /* First register in VUpdate arg array */
1191   int regRec;                     /* Register in which to assemble record */
1192   int regRowid;                   /* Register for ephem table rowid */
1193   int iCsr = pSrc->a[0].iCursor;  /* Cursor used for virtual table scan */
1194   int aDummy[2];                  /* Unused arg for sqlite3WhereOkOnePass() */
1195   int eOnePass;                   /* True to use onepass strategy */
1196   int addr;                       /* Address of OP_OpenEphemeral */
1197
1198   /* Allocate nArg registers in which to gather the arguments for VUpdate. Then
1199   ** create and open the ephemeral table in which the records created from
1200   ** these arguments will be temporarily stored. */
1201   assert( v );
1202   ephemTab = pParse->nTab++;
1203   addr= sqlite3VdbeAddOp2(v, OP_OpenEphemeral, ephemTab, nArg);
1204   regArg = pParse->nMem + 1;
1205   pParse->nMem += nArg;
1206   if( pSrc->nSrc>1 ){
1207     Index *pPk = 0;
1208     Expr *pRow;
1209     ExprList *pList;
1210     if( HasRowid(pTab) ){
1211       if( pRowid ){
1212         pRow = sqlite3ExprDup(db, pRowid, 0);
1213       }else{
1214         pRow = sqlite3PExpr(pParse, TK_ROW, 0, 0);
1215       }
1216     }else{
1217       i16 iPk;      /* PRIMARY KEY column */
1218       pPk = sqlite3PrimaryKeyIndex(pTab);
1219       assert( pPk!=0 );
1220       assert( pPk->nKeyCol==1 );
1221       iPk = pPk->aiColumn[0];
1222       if( aXRef[iPk]>=0 ){
1223         pRow = sqlite3ExprDup(db, pChanges->a[aXRef[iPk]].pExpr, 0);
1224       }else{
1225         pRow = exprRowColumn(pParse, iPk);
1226       }
1227     }
1228     pList = sqlite3ExprListAppend(pParse, 0, pRow);
1229
1230     for(i=0; i<pTab->nCol; i++){
1231       if( aXRef[i]>=0 ){
1232         pList = sqlite3ExprListAppend(pParse, pList,
1233           sqlite3ExprDup(db, pChanges->a[aXRef[i]].pExpr, 0)
1234         );
1235       }else{
1236         pList = sqlite3ExprListAppend(pParse, pList, exprRowColumn(pParse, i));
1237       }
1238     }
1239
1240     updateFromSelect(pParse, ephemTab, pPk, pList, pSrc, pWhere, 0, 0);
1241     sqlite3ExprListDelete(db, pList);
1242     eOnePass = ONEPASS_OFF;
1243   }else{
1244     regRec = ++pParse->nMem;
1245     regRowid = ++pParse->nMem;
1246
1247     /* Start scanning the virtual table */
1248     pWInfo = sqlite3WhereBegin(pParse, pSrc,pWhere,0,0,WHERE_ONEPASS_DESIRED,0);
1249     if( pWInfo==0 ) return;
1250
1251     /* Populate the argument registers. */
1252     for(i=0; i<pTab->nCol; i++){
1253       assert( (pTab->aCol[i].colFlags & COLFLAG_GENERATED)==0 );
1254       if( aXRef[i]>=0 ){
1255         sqlite3ExprCode(pParse, pChanges->a[aXRef[i]].pExpr, regArg+2+i);
1256       }else{
1257         sqlite3VdbeAddOp3(v, OP_VColumn, iCsr, i, regArg+2+i);
1258         sqlite3VdbeChangeP5(v, OPFLAG_NOCHNG);/* For sqlite3_vtab_nochange() */
1259       }
1260     }
1261     if( HasRowid(pTab) ){
1262       sqlite3VdbeAddOp2(v, OP_Rowid, iCsr, regArg);
1263       if( pRowid ){
1264         sqlite3ExprCode(pParse, pRowid, regArg+1);
1265       }else{
1266         sqlite3VdbeAddOp2(v, OP_Rowid, iCsr, regArg+1);
1267       }
1268     }else{
1269       Index *pPk;   /* PRIMARY KEY index */
1270       i16 iPk;      /* PRIMARY KEY column */
1271       pPk = sqlite3PrimaryKeyIndex(pTab);
1272       assert( pPk!=0 );
1273       assert( pPk->nKeyCol==1 );
1274       iPk = pPk->aiColumn[0];
1275       sqlite3VdbeAddOp3(v, OP_VColumn, iCsr, iPk, regArg);
1276       sqlite3VdbeAddOp2(v, OP_SCopy, regArg+2+iPk, regArg+1);
1277     }
1278
1279     eOnePass = sqlite3WhereOkOnePass(pWInfo, aDummy);
1280
1281     /* There is no ONEPASS_MULTI on virtual tables */
1282     assert( eOnePass==ONEPASS_OFF || eOnePass==ONEPASS_SINGLE );
1283
1284     if( eOnePass ){
1285       /* If using the onepass strategy, no-op out the OP_OpenEphemeral coded
1286       ** above. */
1287       sqlite3VdbeChangeToNoop(v, addr);
1288       sqlite3VdbeAddOp1(v, OP_Close, iCsr);
1289     }else{
1290       /* Create a record from the argument register contents and insert it into
1291       ** the ephemeral table. */
1292       sqlite3MultiWrite(pParse);
1293       sqlite3VdbeAddOp3(v, OP_MakeRecord, regArg, nArg, regRec);
1294 #if defined(SQLITE_DEBUG) && !defined(SQLITE_ENABLE_NULL_TRIM)
1295       /* Signal an assert() within OP_MakeRecord that it is allowed to
1296       ** accept no-change records with serial_type 10 */
1297       sqlite3VdbeChangeP5(v, OPFLAG_NOCHNG_MAGIC);
1298 #endif
1299       sqlite3VdbeAddOp2(v, OP_NewRowid, ephemTab, regRowid);
1300       sqlite3VdbeAddOp3(v, OP_Insert, ephemTab, regRec, regRowid);
1301     }
1302   }
1303
1304
1305   if( eOnePass==ONEPASS_OFF ){
1306     /* End the virtual table scan */
1307     if( pSrc->nSrc==1 ){
1308       sqlite3WhereEnd(pWInfo);
1309     }
1310
1311     /* Begin scannning through the ephemeral table. */
1312     addr = sqlite3VdbeAddOp1(v, OP_Rewind, ephemTab); VdbeCoverage(v);
1313
1314     /* Extract arguments from the current row of the ephemeral table and
1315     ** invoke the VUpdate method.  */
1316     for(i=0; i<nArg; i++){
1317       sqlite3VdbeAddOp3(v, OP_Column, ephemTab, i, regArg+i);
1318     }
1319   }
1320   sqlite3VtabMakeWritable(pParse, pTab);
1321   sqlite3VdbeAddOp4(v, OP_VUpdate, 0, nArg, regArg, pVTab, P4_VTAB);
1322   sqlite3VdbeChangeP5(v, onError==OE_Default ? OE_Abort : onError);
1323   sqlite3MayAbort(pParse);
1324
1325   /* End of the ephemeral table scan. Or, if using the onepass strategy,
1326   ** jump to here if the scan visited zero rows. */
1327   if( eOnePass==ONEPASS_OFF ){
1328     sqlite3VdbeAddOp2(v, OP_Next, ephemTab, addr+1); VdbeCoverage(v);
1329     sqlite3VdbeJumpHere(v, addr);
1330     sqlite3VdbeAddOp2(v, OP_Close, ephemTab, 0);
1331   }else{
1332     sqlite3WhereEnd(pWInfo);
1333   }
1334 }
1335 #endif /* SQLITE_OMIT_VIRTUALTABLE */