sqlite3/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 ** $Id$
  16 */
  17 #include "sqliteInt.h"
  18
  19 /*
  20 ** The most recently coded instruction was an OP_Column to retrieve column
  21 ** 'i' of table pTab. This routine sets the P3 parameter of the
  22 ** OP_Column to the default value, if any.
  23 **
  24 ** The default value of a column is specified by a DEFAULT clause in the
  25 ** column definition. This was either supplied by the user when the table
  26 ** was created, or added later to the table definition by an ALTER TABLE
  27 ** command. If the latter, then the row-records in the table btree on disk
  28 ** may not contain a value for the column and the default value, taken
  29 ** from the P3 parameter of the OP_Column instruction, is returned instead.
  30 ** If the former, then all row-records are guaranteed to include a value
  31 ** for the column and the P3 value is not required.
  32 **
  33 ** Column definitions created by an ALTER TABLE command may only have
  34 ** literal default values specified: a number, null or a string. (If a more
  35 ** complicated default expression value was provided, it is evaluated
  36 ** when the ALTER TABLE is executed and one of the literal values written
  37 ** into the sqlite_master table.)
  38 **
  39 ** Therefore, the P3 parameter is only required if the default value for
  40 ** the column is a literal number, string or null. The sqlite3ValueFromExpr()
  41 ** function is capable of transforming these types of expressions into
  42 ** sqlite3_value objects.
  43 */
  44 void sqlite3ColumnDefault(Vdbe *v, Table *pTab, int i){
  45   if( pTab && !pTab->pSelect ){
  46     sqlite3_value *pValue;
  47     u8 enc = sqlite3VdbeDb(v)->enc;
  48     Column *pCol = &pTab->aCol[i];
  49     sqlite3ValueFromExpr(pCol->pDflt, enc, pCol->affinity, &pValue);
  50     sqlite3VdbeChangeP3(v, -1, (const char *)pValue, P3_MEM);
  51   }
  52 }
  53
  54 /*
  55 ** Process an UPDATE statement.
  56 **
  57 **   UPDATE OR IGNORE table_wxyz SET a=b, c=d WHERE e<5 AND f NOT NULL;
  58 **          \_______/ \________/     \______/       \________________/
  59 *            onError   pTabList      pChanges             pWhere
  60 */
  61 void sqlite3Update(
  62   Parse *pParse,         /* The parser context */
  63   SrcList *pTabList,     /* The table in which we should change things */
  64   ExprList *pChanges,    /* Things to be changed */
  65   Expr *pWhere,          /* The WHERE clause.  May be null */
  66   int onError            /* How to handle constraint errors */
  67 ){
  68   int i, j;              /* Loop counters */
  69   Table *pTab;           /* The table to be updated */
  70   int addr = 0;          /* VDBE instruction address of the start of the loop */
  71   WhereInfo *pWInfo;     /* Information about the WHERE clause */
  72   Vdbe *v;               /* The virtual database engine */
  73   Index *pIdx;           /* For looping over indices */
  74   int nIdx;              /* Number of indices that need updating */
  75   int nIdxTotal;         /* Total number of indices */
  76   int iCur;              /* VDBE Cursor number of pTab */
  77   sqlite3 *db;           /* The database structure */
  78   Index **apIdx = 0;     /* An array of indices that need updating too */
  79   char *aIdxUsed = 0;    /* aIdxUsed[i]==1 if the i-th index is used */
  80   int *aXRef = 0;        /* aXRef[i] is the index in pChanges->a[] of the
  81                          ** an expression for the i-th column of the table.
  82                          ** aXRef[i]==-1 if the i-th column is not changed. */
  83   int chngRowid;         /* True if the record number is being changed */
  84   Expr *pRowidExpr = 0;  /* Expression defining the new record number */
  85   int openAll = 0;       /* True if all indices need to be opened */
  86   AuthContext sContext;  /* The authorization context */
  87   NameContext sNC;       /* The name-context to resolve expressions in */
  88
  89 #ifndef SQLITE_OMIT_TRIGGER
  90   int isView;                  /* Trying to update a view */
  91   int triggers_exist = 0;      /* True if any row triggers exist */
  92 #endif
  93
  94   int newIdx      = -1;  /* index of trigger "new" temp table       */
  95   int oldIdx      = -1;  /* index of trigger "old" temp table       */
  96
  97   sContext.pParse = 0;
  98   if( pParse->nErr || sqlite3_malloc_failed ) goto update_cleanup;
  99   db = pParse->db;
 100   assert( pTabList->nSrc==1 );
 101
 102   /* Locate the table which we want to update.
 103   */
 104   pTab = sqlite3SrcListLookup(pParse, pTabList);
 105   if( pTab==0 ) goto update_cleanup;
 106
 107   /* Figure out if we have any triggers and if the table being
 108   ** updated is a view
 109   */
 110 #ifndef SQLITE_OMIT_TRIGGER
 111   triggers_exist = sqlite3TriggersExist(pParse, pTab, TK_UPDATE, pChanges);
 112   isView = pTab->pSelect!=0;
 113 #else
 114 # define triggers_exist 0
 115 # define isView 0
 116 #endif
 117 #ifdef SQLITE_OMIT_VIEW
 118 # undef isView
 119 # define isView 0
 120 #endif
 121
 122   if( sqlite3IsReadOnly(pParse, pTab, triggers_exist) ){
 123     goto update_cleanup;
 124   }
 125   if( isView ){
 126     if( sqlite3ViewGetColumnNames(pParse, pTab) ){
 127       goto update_cleanup;
 128     }
 129   }
 130   aXRef = sqliteMallocRaw( sizeof(int) * pTab->nCol );
 131   if( aXRef==0 ) goto update_cleanup;
 132   for(i=0; i<pTab->nCol; i++) aXRef[i] = -1;
 133
 134   /* If there are FOR EACH ROW triggers, allocate cursors for the
 135   ** special OLD and NEW tables
 136   */
 137   if( triggers_exist ){
 138     newIdx = pParse->nTab++;
 139     oldIdx = pParse->nTab++;
 140   }
 141
 142   /* Allocate a cursors for the main database table and for all indices.
 143   ** The index cursors might not be used, but if they are used they
 144   ** need to occur right after the database cursor.  So go ahead and
 145   ** allocate enough space, just in case.
 146   */
 147   pTabList->a[0].iCursor = iCur = pParse->nTab++;
 148   for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
 149     pParse->nTab++;
 150   }
 151
 152   /* Initialize the name-context */
 153   memset(&sNC, 0, sizeof(sNC));
 154   sNC.pParse = pParse;
 155   sNC.pSrcList = pTabList;
 156
 157   /* Resolve the column names in all the expressions of the
 158   ** of the UPDATE statement.  Also find the column index
 159   ** for each column to be updated in the pChanges array.  For each
 160   ** column to be updated, make sure we have authorization to change
 161   ** that column.
 162   */
 163   chngRowid = 0;
 164   for(i=0; i<pChanges->nExpr; i++){
 165     if( sqlite3ExprResolveNames(&sNC, pChanges->a[i].pExpr) ){
 166       goto update_cleanup;
 167     }
 168     for(j=0; j<pTab->nCol; j++){
 169       if( sqlite3StrICmp(pTab->aCol[j].zName, pChanges->a[i].zName)==0 ){
 170         if( j==pTab->iPKey ){
 171           chngRowid = 1;
 172           pRowidExpr = pChanges->a[i].pExpr;
 173         }
 174         aXRef[j] = i;
 175         break;
 176       }
 177     }
 178     if( j>=pTab->nCol ){
 179       if( sqlite3IsRowid(pChanges->a[i].zName) ){
 180         chngRowid = 1;
 181         pRowidExpr = pChanges->a[i].pExpr;
 182       }else{
 183         sqlite3ErrorMsg(pParse, "no such column: %s", pChanges->a[i].zName);
 184         goto update_cleanup;
 185       }
 186     }
 187 #ifndef SQLITE_OMIT_AUTHORIZATION
 188     {
 189       int rc;
 190       rc = sqlite3AuthCheck(pParse, SQLITE_UPDATE, pTab->zName,
 191                            pTab->aCol[j].zName, db->aDb[pTab->iDb].zName);
 192       if( rc==SQLITE_DENY ){
 193         goto update_cleanup;
 194       }else if( rc==SQLITE_IGNORE ){
 195         aXRef[j] = -1;
 196       }
 197     }
 198 #endif
 199   }
 200
 201   /* Allocate memory for the array apIdx[] and fill it with pointers to every
 202   ** index that needs to be updated.  Indices only need updating if their
 203   ** key includes one of the columns named in pChanges or if the record
 204   ** number of the original table entry is changing.
 205   */
 206   for(nIdx=nIdxTotal=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, nIdxTotal++){
 207     if( chngRowid ){
 208       i = 0;
 209     }else {
 210       for(i=0; i<pIdx->nColumn; i++){
 211         if( aXRef[pIdx->aiColumn[i]]>=0 ) break;
 212       }
 213     }
 214     if( i<pIdx->nColumn ) nIdx++;
 215   }
 216   if( nIdxTotal>0 ){
 217     apIdx = sqliteMallocRaw( sizeof(Index*) * nIdx + nIdxTotal );
 218     if( apIdx==0 ) goto update_cleanup;
 219     aIdxUsed = (char*)&apIdx[nIdx];
 220   }
 221   for(nIdx=j=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, j++){
 222     if( chngRowid ){
 223       i = 0;
 224     }else{
 225       for(i=0; i<pIdx->nColumn; i++){
 226         if( aXRef[pIdx->aiColumn[i]]>=0 ) break;
 227       }
 228     }
 229     if( i<pIdx->nColumn ){
 230       if( sqlite3CheckIndexCollSeq(pParse, pIdx) ) goto update_cleanup;
 231       apIdx[nIdx++] = pIdx;
 232       aIdxUsed[j] = 1;
 233     }else{
 234       aIdxUsed[j] = 0;
 235     }
 236   }
 237
 238   /* Resolve the column names in all the expressions in the
 239   ** WHERE clause.
 240   */
 241   if( sqlite3ExprResolveNames(&sNC, pWhere) ){
 242     goto update_cleanup;
 243   }
 244
 245   /* Start the view context
 246   */
 247   if( isView ){
 248     sqlite3AuthContextPush(pParse, &sContext, pTab->zName);
 249   }
 250
 251   /* Begin generating code.
 252   */
 253   v = sqlite3GetVdbe(pParse);
 254   if( v==0 ) goto update_cleanup;
 255   if( pParse->nested==0 ) sqlite3VdbeCountChanges(v);
 256   sqlite3BeginWriteOperation(pParse, 1, pTab->iDb);
 257
 258   /* If we are trying to update a view, construct that view into
 259   ** a temporary table.
 260   */
 261   if( isView ){
 262     Select *pView;
 263     pView = sqlite3SelectDup(pTab->pSelect);
 264     sqlite3Select(pParse, pView, SRT_TempTable, iCur, 0, 0, 0, 0);
 265     sqlite3SelectDelete(pView);
 266   }
 267
 268   /* Begin the database scan
 269   */
 270   pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, 0);
 271   if( pWInfo==0 ) goto update_cleanup;
 272
 273   /* Remember the index of every item to be updated.
 274   */
 275   sqlite3VdbeAddOp(v, OP_Rowid, iCur, 0);
 276   sqlite3VdbeAddOp(v, OP_ListWrite, 0, 0);
 277
 278   /* End the database scan loop.
 279   */
 280   sqlite3WhereEnd(pWInfo);
 281
 282   /* Initialize the count of updated rows
 283   */
 284   if( db->flags & SQLITE_CountRows && !pParse->trigStack ){
 285     sqlite3VdbeAddOp(v, OP_Integer, 0, 0);
 286   }
 287
 288   if( triggers_exist ){
 289     /* Create pseudo-tables for NEW and OLD
 290     */
 291     sqlite3VdbeAddOp(v, OP_OpenPseudo, oldIdx, 0);
 292     sqlite3VdbeAddOp(v, OP_SetNumColumns, oldIdx, pTab->nCol);
 293     sqlite3VdbeAddOp(v, OP_OpenPseudo, newIdx, 0);
 294     sqlite3VdbeAddOp(v, OP_SetNumColumns, newIdx, pTab->nCol);
 295
 296     /* The top of the update loop for when there are triggers.
 297     */
 298     sqlite3VdbeAddOp(v, OP_ListRewind, 0, 0);
 299     addr = sqlite3VdbeAddOp(v, OP_ListRead, 0, 0);
 300
 301     if( !isView ){
 302       sqlite3VdbeAddOp(v, OP_Dup, 0, 0);
 303       sqlite3VdbeAddOp(v, OP_Dup, 0, 0);
 304       /* Open a cursor and make it point to the record that is
 305       ** being updated.
 306       */
 307       sqlite3OpenTableForReading(v, iCur, pTab);
 308     }
 309     sqlite3VdbeAddOp(v, OP_MoveGe, iCur, 0);
 310
 311     /* Generate the OLD table
 312     */
 313     sqlite3VdbeAddOp(v, OP_Rowid, iCur, 0);
 314     sqlite3VdbeAddOp(v, OP_RowData, iCur, 0);
 315     sqlite3VdbeAddOp(v, OP_Insert, oldIdx, 0);
 316
 317     /* Generate the NEW table
 318     */
 319     if( chngRowid ){
 320       sqlite3ExprCodeAndCache(pParse, pRowidExpr);
 321     }else{
 322       sqlite3VdbeAddOp(v, OP_Rowid, iCur, 0);
 323     }
 324     for(i=0; i<pTab->nCol; i++){
 325       if( i==pTab->iPKey ){
 326         sqlite3VdbeAddOp(v, OP_Null, 0, 0);
 327         continue;
 328       }
 329       j = aXRef[i];
 330       if( j<0 ){
 331         sqlite3VdbeAddOp(v, OP_Column, iCur, i);
 332         sqlite3ColumnDefault(v, pTab, i);
 333       }else{
 334         sqlite3ExprCodeAndCache(pParse, pChanges->a[j].pExpr);
 335       }
 336     }
 337     sqlite3VdbeAddOp(v, OP_MakeRecord, pTab->nCol, 0);
 338     if( !isView ){
 339       sqlite3TableAffinityStr(v, pTab);
 340     }
 341     if( pParse->nErr ) goto update_cleanup;
 342     sqlite3VdbeAddOp(v, OP_Insert, newIdx, 0);
 343     if( !isView ){
 344       sqlite3VdbeAddOp(v, OP_Close, iCur, 0);
 345     }
 346
 347     /* Fire the BEFORE and INSTEAD OF triggers
 348     */
 349     if( sqlite3CodeRowTrigger(pParse, TK_UPDATE, pChanges, TRIGGER_BEFORE, pTab,
 350           newIdx, oldIdx, onError, addr) ){
 351       goto update_cleanup;
 352     }
 353   }
 354
 355   if( !isView ){
 356     /*
 357     ** Open every index that needs updating.  Note that if any
 358     ** index could potentially invoke a REPLACE conflict resolution
 359     ** action, then we need to open all indices because we might need
 360     ** to be deleting some records.
 361     */
 362     sqlite3VdbeAddOp(v, OP_Integer, pTab->iDb, 0);
 363     sqlite3VdbeAddOp(v, OP_OpenWrite, iCur, pTab->tnum);
 364     sqlite3VdbeAddOp(v, OP_SetNumColumns, iCur, pTab->nCol);
 365     if( onError==OE_Replace ){
 366       openAll = 1;
 367     }else{
 368       openAll = 0;
 369       for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
 370         if( pIdx->onError==OE_Replace ){
 371           openAll = 1;
 372           break;
 373         }
 374       }
 375     }
 376     for(i=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){
 377       if( openAll || aIdxUsed[i] ){
 378         sqlite3VdbeAddOp(v, OP_Integer, pIdx->iDb, 0);
 379         sqlite3VdbeOp3(v, OP_OpenWrite, iCur+i+1, pIdx->tnum,
 380                        (char*)&pIdx->keyInfo, P3_KEYINFO);
 381         assert( pParse->nTab>iCur+i+1 );
 382       }
 383     }
 384
 385     /* Loop over every record that needs updating.  We have to load
 386     ** the old data for each record to be updated because some columns
 387     ** might not change and we will need to copy the old value.
 388     ** Also, the old data is needed to delete the old index entires.
 389     ** So make the cursor point at the old record.
 390     */
 391     if( !triggers_exist ){
 392       sqlite3VdbeAddOp(v, OP_ListRewind, 0, 0);
 393       addr = sqlite3VdbeAddOp(v, OP_ListRead, 0, 0);
 394       sqlite3VdbeAddOp(v, OP_Dup, 0, 0);
 395     }
 396     sqlite3VdbeAddOp(v, OP_NotExists, iCur, addr);
 397
 398     /* If the record number will change, push the record number as it
 399     ** will be after the update. (The old record number is currently
 400     ** on top of the stack.)
 401     */
 402     if( chngRowid ){
 403       sqlite3ExprCode(pParse, pRowidExpr);
 404       sqlite3VdbeAddOp(v, OP_MustBeInt, 0, 0);
 405     }
 406
 407     /* Compute new data for this record.
 408     */
 409     for(i=0; i<pTab->nCol; i++){
 410       if( i==pTab->iPKey ){
 411         sqlite3VdbeAddOp(v, OP_Null, 0, 0);
 412         continue;
 413       }
 414       j = aXRef[i];
 415       if( j<0 ){
 416         sqlite3VdbeAddOp(v, OP_Column, iCur, i);
 417         sqlite3ColumnDefault(v, pTab, i);
 418       }else{
 419         sqlite3ExprCode(pParse, pChanges->a[j].pExpr);
 420       }
 421     }
 422
 423     /* Do constraint checks
 424     */
 425     sqlite3GenerateConstraintChecks(pParse, pTab, iCur, aIdxUsed, chngRowid, 1,
 426                                    onError, addr);
 427
 428     /* Delete the old indices for the current record.
 429     */
 430     sqlite3GenerateRowIndexDelete(db, v, pTab, iCur, aIdxUsed);
 431
 432     /* If changing the record number, delete the old record.
 433     */
 434     if( chngRowid ){
 435       sqlite3VdbeAddOp(v, OP_Delete, iCur, 0);
 436     }
 437
 438     /* Create the new index entries and the new record.
 439     */
 440     sqlite3CompleteInsertion(pParse, pTab, iCur, aIdxUsed, chngRowid, 1, -1);
 441   }
 442
 443   /* Increment the row counter
 444   */
 445   if( db->flags & SQLITE_CountRows && !pParse->trigStack){
 446     sqlite3VdbeAddOp(v, OP_AddImm, 1, 0);
 447   }
 448
 449   /* If there are triggers, close all the cursors after each iteration
 450   ** through the loop.  The fire the after triggers.
 451   */
 452   if( triggers_exist ){
 453     if( !isView ){
 454       for(i=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){
 455         if( openAll || aIdxUsed[i] )
 456           sqlite3VdbeAddOp(v, OP_Close, iCur+i+1, 0);
 457       }
 458       sqlite3VdbeAddOp(v, OP_Close, iCur, 0);
 459     }
 460     if( sqlite3CodeRowTrigger(pParse, TK_UPDATE, pChanges, TRIGGER_AFTER, pTab,
 461           newIdx, oldIdx, onError, addr) ){
 462       goto update_cleanup;
 463     }
 464   }
 465
 466   /* Repeat the above with the next record to be updated, until
 467   ** all record selected by the WHERE clause have been updated.
 468   */
 469   sqlite3VdbeAddOp(v, OP_Goto, 0, addr);
 470   sqlite3VdbeChangeP2(v, addr, sqlite3VdbeCurrentAddr(v));
 471   sqlite3VdbeAddOp(v, OP_ListReset, 0, 0);
 472
 473   /* Close all tables if there were no FOR EACH ROW triggers */
 474   if( !triggers_exist ){
 475     for(i=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){
 476       if( openAll || aIdxUsed[i] ){
 477         sqlite3VdbeAddOp(v, OP_Close, iCur+i+1, 0);
 478       }
 479     }
 480     sqlite3VdbeAddOp(v, OP_Close, iCur, 0);
 481   }else{
 482     sqlite3VdbeAddOp(v, OP_Close, newIdx, 0);
 483     sqlite3VdbeAddOp(v, OP_Close, oldIdx, 0);
 484   }
 485
 486   /*
 487   ** Return the number of rows that were changed. If this routine is
 488   ** generating code because of a call to sqlite3NestedParse(), do not
 489   ** invoke the callback function.
 490   */
 491   if( db->flags & SQLITE_CountRows && !pParse->trigStack && pParse->nested==0 ){
 492     sqlite3VdbeAddOp(v, OP_Callback, 1, 0);
 493     sqlite3VdbeSetNumCols(v, 1);
 494     sqlite3VdbeSetColName(v, 0, "rows updated", P3_STATIC);
 495   }
 496
 497 update_cleanup:
 498   sqlite3AuthContextPop(&sContext);
 499   sqliteFree(apIdx);
 500   sqliteFree(aXRef);
 501   sqlite3SrcListDelete(pTabList);
 502   sqlite3ExprListDelete(pChanges);
 503   sqlite3ExprDelete(pWhere);
 504   return;
 505 }