src/trigger.c

   1 /*
   2 **
   3 ** The author disclaims copyright to this source code.  In place of
   4 ** a legal notice, here is a blessing:
   5 **
   6 **    May you do good and not evil.
   7 **    May you find forgiveness for yourself and forgive others.
   8 **    May you share freely, never taking more than you give.
   9 **
  10 *************************************************************************
  11 ** This file contains the implementation for TRIGGERs
  12 */
  13 #include "sqliteInt.h"
  14
  15 #ifndef SQLITE_OMIT_TRIGGER
  16 /*
  17 ** Delete a linked list of TriggerStep structures.
  18 */
  19 void sqlite3DeleteTriggerStep(sqlite3 *db, TriggerStep *pTriggerStep){
  20   while( pTriggerStep ){
  21     TriggerStep * pTmp = pTriggerStep;
  22     pTriggerStep = pTriggerStep->pNext;
  23
  24     sqlite3ExprDelete(db, pTmp->pWhere);
  25     sqlite3ExprListDelete(db, pTmp->pExprList);
  26     sqlite3SelectDelete(db, pTmp->pSelect);
  27     sqlite3IdListDelete(db, pTmp->pIdList);
  28     sqlite3UpsertDelete(db, pTmp->pUpsert);
  29     sqlite3DbFree(db, pTmp->zSpan);
  30
  31     sqlite3DbFree(db, pTmp);
  32   }
  33 }
  34
  35 /*
  36 ** Given table pTab, return a list of all the triggers attached to
  37 ** the table. The list is connected by Trigger.pNext pointers.
  38 **
  39 ** All of the triggers on pTab that are in the same database as pTab
  40 ** are already attached to pTab->pTrigger.  But there might be additional
  41 ** triggers on pTab in the TEMP schema.  This routine prepends all
  42 ** TEMP triggers on pTab to the beginning of the pTab->pTrigger list
  43 ** and returns the combined list.
  44 **
  45 ** To state it another way:  This routine returns a list of all triggers
  46 ** that fire off of pTab.  The list will include any TEMP triggers on
  47 ** pTab as well as the triggers lised in pTab->pTrigger.
  48 */
  49 Trigger *sqlite3TriggerList(Parse *pParse, Table *pTab){
  50   Schema * const pTmpSchema = pParse->db->aDb[1].pSchema;
  51   Trigger *pList = 0;                  /* List of triggers to return */
  52
  53   if( pParse->disableTriggers ){
  54     return 0;
  55   }
  56
  57   if( pTmpSchema!=pTab->pSchema ){
  58     HashElem *p;
  59     assert( sqlite3SchemaMutexHeld(pParse->db, 0, pTmpSchema) );
  60     for(p=sqliteHashFirst(&pTmpSchema->trigHash); p; p=sqliteHashNext(p)){
  61       Trigger *pTrig = (Trigger *)sqliteHashData(p);
  62       if( pTrig->pTabSchema==pTab->pSchema
  63        && 0==sqlite3StrICmp(pTrig->table, pTab->zName)
  64       ){
  65         pTrig->pNext = (pList ? pList : pTab->pTrigger);
  66         pList = pTrig;
  67       }
  68     }
  69   }
  70
  71   return (pList ? pList : pTab->pTrigger);
  72 }
  73
  74 /*
  75 ** This is called by the parser when it sees a CREATE TRIGGER statement
  76 ** up to the point of the BEGIN before the trigger actions.  A Trigger
  77 ** structure is generated based on the information available and stored
  78 ** in pParse->pNewTrigger.  After the trigger actions have been parsed, the
  79 ** sqlite3FinishTrigger() function is called to complete the trigger
  80 ** construction process.
  81 */
  82 void sqlite3BeginTrigger(
  83   Parse *pParse,      /* The parse context of the CREATE TRIGGER statement */
  84   Token *pName1,      /* The name of the trigger */
  85   Token *pName2,      /* The name of the trigger */
  86   int tr_tm,          /* One of TK_BEFORE, TK_AFTER, TK_INSTEAD */
  87   int op,             /* One of TK_INSERT, TK_UPDATE, TK_DELETE */
  88   IdList *pColumns,   /* column list if this is an UPDATE OF trigger */
  89   SrcList *pTableName,/* The name of the table/view the trigger applies to */
  90   Expr *pWhen,        /* WHEN clause */
  91   int isTemp,         /* True if the TEMPORARY keyword is present */
  92   int noErr           /* Suppress errors if the trigger already exists */
  93 ){
  94   Trigger *pTrigger = 0;  /* The new trigger */
  95   Table *pTab;            /* Table that the trigger fires off of */
  96   char *zName = 0;        /* Name of the trigger */
  97   sqlite3 *db = pParse->db;  /* The database connection */
  98   int iDb;                /* The database to store the trigger in */
  99   Token *pName;           /* The unqualified db name */
 100   DbFixer sFix;           /* State vector for the DB fixer */
 101
 102   assert( pName1!=0 );   /* pName1->z might be NULL, but not pName1 itself */
 103   assert( pName2!=0 );
 104   assert( op==TK_INSERT || op==TK_UPDATE || op==TK_DELETE );
 105   assert( op>0 && op<0xff );
 106   if( isTemp ){
 107     /* If TEMP was specified, then the trigger name may not be qualified. */
 108     if( pName2->n>0 ){
 109       sqlite3ErrorMsg(pParse, "temporary trigger may not have qualified name");
 110       goto trigger_cleanup;
 111     }
 112     iDb = 1;
 113     pName = pName1;
 114   }else{
 115     /* Figure out the db that the trigger will be created in */
 116     iDb = sqlite3TwoPartName(pParse, pName1, pName2, &pName);
 117     if( iDb<0 ){
 118       goto trigger_cleanup;
 119     }
 120   }
 121   if( !pTableName || db->mallocFailed ){
 122     goto trigger_cleanup;
 123   }
 124
 125   /* A long-standing parser bug is that this syntax was allowed:
 126   **
 127   **    CREATE TRIGGER attached.demo AFTER INSERT ON attached.tab ....
 128   **                                                 ^^^^^^^^
 129   **
 130   ** To maintain backwards compatibility, ignore the database
 131   ** name on pTableName if we are reparsing out of SQLITE_MASTER.
 132   */
 133   if( db->init.busy && iDb!=1 ){
 134     sqlite3DbFree(db, pTableName->a[0].zDatabase);
 135     pTableName->a[0].zDatabase = 0;
 136   }
 137
 138   /* If the trigger name was unqualified, and the table is a temp table,
 139   ** then set iDb to 1 to create the trigger in the temporary database.
 140   ** If sqlite3SrcListLookup() returns 0, indicating the table does not
 141   ** exist, the error is caught by the block below.
 142   */
 143   pTab = sqlite3SrcListLookup(pParse, pTableName);
 144   if( db->init.busy==0 && pName2->n==0 && pTab
 145         && pTab->pSchema==db->aDb[1].pSchema ){
 146     iDb = 1;
 147   }
 148
 149   /* Ensure the table name matches database name and that the table exists */
 150   if( db->mallocFailed ) goto trigger_cleanup;
 151   assert( pTableName->nSrc==1 );
 152   sqlite3FixInit(&sFix, pParse, iDb, "trigger", pName);
 153   if( sqlite3FixSrcList(&sFix, pTableName) ){
 154     goto trigger_cleanup;
 155   }
 156   pTab = sqlite3SrcListLookup(pParse, pTableName);
 157   if( !pTab ){
 158     /* The table does not exist. */
 159     if( db->init.iDb==1 ){
 160       /* Ticket #3810.
 161       ** Normally, whenever a table is dropped, all associated triggers are
 162       ** dropped too.  But if a TEMP trigger is created on a non-TEMP table
 163       ** and the table is dropped by a different database connection, the
 164       ** trigger is not visible to the database connection that does the
 165       ** drop so the trigger cannot be dropped.  This results in an
 166       ** "orphaned trigger" - a trigger whose associated table is missing.
 167       */
 168       db->init.orphanTrigger = 1;
 169     }
 170     goto trigger_cleanup;
 171   }
 172   if( IsVirtual(pTab) ){
 173     sqlite3ErrorMsg(pParse, "cannot create triggers on virtual tables");
 174     goto trigger_cleanup;
 175   }
 176
 177   /* Check that the trigger name is not reserved and that no trigger of the
 178   ** specified name exists */
 179   zName = sqlite3NameFromToken(db, pName);
 180   if( !zName || SQLITE_OK!=sqlite3CheckObjectName(pParse, zName) ){
 181     goto trigger_cleanup;
 182   }
 183   assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
 184   if( sqlite3HashFind(&(db->aDb[iDb].pSchema->trigHash),zName) ){
 185     if( !noErr ){
 186       sqlite3ErrorMsg(pParse, "trigger %T already exists", pName);
 187     }else{
 188       assert( !db->init.busy );
 189       sqlite3CodeVerifySchema(pParse, iDb);
 190     }
 191     goto trigger_cleanup;
 192   }
 193
 194   /* Do not create a trigger on a system table */
 195   if( sqlite3StrNICmp(pTab->zName, "sqlite_", 7)==0 ){
 196     sqlite3ErrorMsg(pParse, "cannot create trigger on system table");
 197     goto trigger_cleanup;
 198   }
 199
 200   /* INSTEAD of triggers are only for views and views only support INSTEAD
 201   ** of triggers.
 202   */
 203   if( pTab->pSelect && tr_tm!=TK_INSTEAD ){
 204     sqlite3ErrorMsg(pParse, "cannot create %s trigger on view: %S",
 205         (tr_tm == TK_BEFORE)?"BEFORE":"AFTER", pTableName, 0);
 206     goto trigger_cleanup;
 207   }
 208   if( !pTab->pSelect && tr_tm==TK_INSTEAD ){
 209     sqlite3ErrorMsg(pParse, "cannot create INSTEAD OF"
 210         " trigger on table: %S", pTableName, 0);
 211     goto trigger_cleanup;
 212   }
 213
 214 #ifndef SQLITE_OMIT_AUTHORIZATION
 215   {
 216     int iTabDb = sqlite3SchemaToIndex(db, pTab->pSchema);
 217     int code = SQLITE_CREATE_TRIGGER;
 218     const char *zDb = db->aDb[iTabDb].zDbSName;
 219     const char *zDbTrig = isTemp ? db->aDb[1].zDbSName : zDb;
 220     if( iTabDb==1 || isTemp ) code = SQLITE_CREATE_TEMP_TRIGGER;
 221     if( sqlite3AuthCheck(pParse, code, zName, pTab->zName, zDbTrig) ){
 222       goto trigger_cleanup;
 223     }
 224     if( sqlite3AuthCheck(pParse, SQLITE_INSERT, SCHEMA_TABLE(iTabDb),0,zDb)){
 225       goto trigger_cleanup;
 226     }
 227   }
 228 #endif
 229
 230   /* INSTEAD OF triggers can only appear on views and BEFORE triggers
 231   ** cannot appear on views.  So we might as well translate every
 232   ** INSTEAD OF trigger into a BEFORE trigger.  It simplifies code
 233   ** elsewhere.
 234   */
 235   if (tr_tm == TK_INSTEAD){
 236     tr_tm = TK_BEFORE;
 237   }
 238
 239   /* Build the Trigger object */
 240   pTrigger = (Trigger*)sqlite3DbMallocZero(db, sizeof(Trigger));
 241   if( pTrigger==0 ) goto trigger_cleanup;
 242   pTrigger->zName = zName;
 243   zName = 0;
 244   pTrigger->table = sqlite3DbStrDup(db, pTableName->a[0].zName);
 245   pTrigger->pSchema = db->aDb[iDb].pSchema;
 246   pTrigger->pTabSchema = pTab->pSchema;
 247   pTrigger->op = (u8)op;
 248   pTrigger->tr_tm = tr_tm==TK_BEFORE ? TRIGGER_BEFORE : TRIGGER_AFTER;
 249   pTrigger->pWhen = sqlite3ExprDup(db, pWhen, EXPRDUP_REDUCE);
 250   pTrigger->pColumns = sqlite3IdListDup(db, pColumns);
 251   assert( pParse->pNewTrigger==0 );
 252   pParse->pNewTrigger = pTrigger;
 253
 254 trigger_cleanup:
 255   sqlite3DbFree(db, zName);
 256   sqlite3SrcListDelete(db, pTableName);
 257   sqlite3IdListDelete(db, pColumns);
 258   sqlite3ExprDelete(db, pWhen);
 259   if( !pParse->pNewTrigger ){
 260     sqlite3DeleteTrigger(db, pTrigger);
 261   }else{
 262     assert( pParse->pNewTrigger==pTrigger );
 263   }
 264 }
 265
 266 /*
 267 ** This routine is called after all of the trigger actions have been parsed
 268 ** in order to complete the process of building the trigger.
 269 */
 270 void sqlite3FinishTrigger(
 271   Parse *pParse,          /* Parser context */
 272   TriggerStep *pStepList, /* The triggered program */
 273   Token *pAll             /* Token that describes the complete CREATE TRIGGER */
 274 ){
 275   Trigger *pTrig = pParse->pNewTrigger;   /* Trigger being finished */
 276   char *zName;                            /* Name of trigger */
 277   sqlite3 *db = pParse->db;               /* The database */
 278   DbFixer sFix;                           /* Fixer object */
 279   int iDb;                                /* Database containing the trigger */
 280   Token nameToken;                        /* Trigger name for error reporting */
 281
 282   pParse->pNewTrigger = 0;
 283   if( NEVER(pParse->nErr) || !pTrig ) goto triggerfinish_cleanup;
 284   zName = pTrig->zName;
 285   iDb = sqlite3SchemaToIndex(pParse->db, pTrig->pSchema);
 286   pTrig->step_list = pStepList;
 287   while( pStepList ){
 288     pStepList->pTrig = pTrig;
 289     pStepList = pStepList->pNext;
 290   }
 291   sqlite3TokenInit(&nameToken, pTrig->zName);
 292   sqlite3FixInit(&sFix, pParse, iDb, "trigger", &nameToken);
 293   if( sqlite3FixTriggerStep(&sFix, pTrig->step_list)
 294    || sqlite3FixExpr(&sFix, pTrig->pWhen)
 295   ){
 296     goto triggerfinish_cleanup;
 297   }
 298
 299   /* if we are not initializing,
 300   ** build the sqlite_master entry
 301   */
 302   if( !db->init.busy ){
 303     Vdbe *v;
 304     char *z;
 305
 306     /* Make an entry in the sqlite_master table */
 307     v = sqlite3GetVdbe(pParse);
 308     if( v==0 ) goto triggerfinish_cleanup;
 309     sqlite3BeginWriteOperation(pParse, 0, iDb);
 310     z = sqlite3DbStrNDup(db, (char*)pAll->z, pAll->n);
 311     testcase( z==0 );
 312     sqlite3NestedParse(pParse,
 313        "INSERT INTO %Q.%s VALUES('trigger',%Q,%Q,0,'CREATE TRIGGER %q')",
 314        db->aDb[iDb].zDbSName, MASTER_NAME, zName,
 315        pTrig->table, z);
 316     sqlite3DbFree(db, z);
 317     sqlite3ChangeCookie(pParse, iDb);
 318     sqlite3VdbeAddParseSchemaOp(v, iDb,
 319         sqlite3MPrintf(db, "type='trigger' AND name='%q'", zName));
 320   }
 321
 322   if( db->init.busy ){
 323     Trigger *pLink = pTrig;
 324     Hash *pHash = &db->aDb[iDb].pSchema->trigHash;
 325     assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
 326     pTrig = sqlite3HashInsert(pHash, zName, pTrig);
 327     if( pTrig ){
 328       sqlite3OomFault(db);
 329     }else if( pLink->pSchema==pLink->pTabSchema ){
 330       Table *pTab;
 331       pTab = sqlite3HashFind(&pLink->pTabSchema->tblHash, pLink->table);
 332       assert( pTab!=0 );
 333       pLink->pNext = pTab->pTrigger;
 334       pTab->pTrigger = pLink;
 335     }
 336   }
 337
 338 triggerfinish_cleanup:
 339   sqlite3DeleteTrigger(db, pTrig);
 340   assert( !pParse->pNewTrigger );
 341   sqlite3DeleteTriggerStep(db, pStepList);
 342 }
 343
 344 /*
 345 ** Duplicate a range of text from an SQL statement, then convert all
 346 ** whitespace characters into ordinary space characters.
 347 */
 348 static char *triggerSpanDup(sqlite3 *db, const char *zStart, const char *zEnd){
 349   char *z = sqlite3DbSpanDup(db, zStart, zEnd);
 350   int i;
 351   if( z ) for(i=0; z[i]; i++) if( sqlite3Isspace(z[i]) ) z[i] = ' ';
 352   return z;
 353 }
 354
 355 /*
 356 ** Turn a SELECT statement (that the pSelect parameter points to) into
 357 ** a trigger step.  Return a pointer to a TriggerStep structure.
 358 **
 359 ** The parser calls this routine when it finds a SELECT statement in
 360 ** body of a TRIGGER.
 361 */
 362 TriggerStep *sqlite3TriggerSelectStep(
 363   sqlite3 *db,                /* Database connection */
 364   Select *pSelect,            /* The SELECT statement */
 365   const char *zStart,         /* Start of SQL text */
 366   const char *zEnd            /* End of SQL text */
 367 ){
 368   TriggerStep *pTriggerStep = sqlite3DbMallocZero(db, sizeof(TriggerStep));
 369   if( pTriggerStep==0 ) {
 370     sqlite3SelectDelete(db, pSelect);
 371     return 0;
 372   }
 373   pTriggerStep->op = TK_SELECT;
 374   pTriggerStep->pSelect = pSelect;
 375   pTriggerStep->orconf = OE_Default;
 376   pTriggerStep->zSpan = triggerSpanDup(db, zStart, zEnd);
 377   return pTriggerStep;
 378 }
 379
 380 /*
 381 ** Allocate space to hold a new trigger step.  The allocated space
 382 ** holds both the TriggerStep object and the TriggerStep.target.z string.
 383 **
 384 ** If an OOM error occurs, NULL is returned and db->mallocFailed is set.
 385 */
 386 static TriggerStep *triggerStepAllocate(
 387   sqlite3 *db,                /* Database connection */
 388   u8 op,                      /* Trigger opcode */
 389   Token *pName,               /* The target name */
 390   const char *zStart,         /* Start of SQL text */
 391   const char *zEnd            /* End of SQL text */
 392 ){
 393   TriggerStep *pTriggerStep;
 394
 395   pTriggerStep = sqlite3DbMallocZero(db, sizeof(TriggerStep) + pName->n + 1);
 396   if( pTriggerStep ){
 397     char *z = (char*)&pTriggerStep[1];
 398     memcpy(z, pName->z, pName->n);
 399     sqlite3Dequote(z);
 400     pTriggerStep->zTarget = z;
 401     pTriggerStep->op = op;
 402     pTriggerStep->zSpan = triggerSpanDup(db, zStart, zEnd);
 403   }
 404   return pTriggerStep;
 405 }
 406
 407 /*
 408 ** Build a trigger step out of an INSERT statement.  Return a pointer
 409 ** to the new trigger step.
 410 **
 411 ** The parser calls this routine when it sees an INSERT inside the
 412 ** body of a trigger.
 413 */
 414 TriggerStep *sqlite3TriggerInsertStep(
 415   sqlite3 *db,        /* The database connection */
 416   Token *pTableName,  /* Name of the table into which we insert */
 417   IdList *pColumn,    /* List of columns in pTableName to insert into */
 418   Select *pSelect,    /* A SELECT statement that supplies values */
 419   u8 orconf,          /* The conflict algorithm (OE_Abort, OE_Replace, etc.) */
 420   Upsert *pUpsert,    /* ON CONFLICT clauses for upsert */
 421   const char *zStart, /* Start of SQL text */
 422   const char *zEnd    /* End of SQL text */
 423 ){
 424   TriggerStep *pTriggerStep;
 425
 426   assert(pSelect != 0 || db->mallocFailed);
 427
 428   pTriggerStep = triggerStepAllocate(db, TK_INSERT, pTableName, zStart, zEnd);
 429   if( pTriggerStep ){
 430     pTriggerStep->pSelect = sqlite3SelectDup(db, pSelect, EXPRDUP_REDUCE);
 431     pTriggerStep->pIdList = pColumn;
 432     pTriggerStep->pUpsert = pUpsert;
 433     pTriggerStep->orconf = orconf;
 434   }else{
 435     testcase( pColumn );
 436     sqlite3IdListDelete(db, pColumn);
 437     testcase( pUpsert );
 438     sqlite3UpsertDelete(db, pUpsert);
 439   }
 440   sqlite3SelectDelete(db, pSelect);
 441
 442   return pTriggerStep;
 443 }
 444
 445 /*
 446 ** Construct a trigger step that implements an UPDATE statement and return
 447 ** a pointer to that trigger step.  The parser calls this routine when it
 448 ** sees an UPDATE statement inside the body of a CREATE TRIGGER.
 449 */
 450 TriggerStep *sqlite3TriggerUpdateStep(
 451   sqlite3 *db,         /* The database connection */
 452   Token *pTableName,   /* Name of the table to be updated */
 453   ExprList *pEList,    /* The SET clause: list of column and new values */
 454   Expr *pWhere,        /* The WHERE clause */
 455   u8 orconf,           /* The conflict algorithm. (OE_Abort, OE_Ignore, etc) */
 456   const char *zStart,  /* Start of SQL text */
 457   const char *zEnd     /* End of SQL text */
 458 ){
 459   TriggerStep *pTriggerStep;
 460
 461   pTriggerStep = triggerStepAllocate(db, TK_UPDATE, pTableName, zStart, zEnd);
 462   if( pTriggerStep ){
 463     pTriggerStep->pExprList = sqlite3ExprListDup(db, pEList, EXPRDUP_REDUCE);
 464     pTriggerStep->pWhere = sqlite3ExprDup(db, pWhere, EXPRDUP_REDUCE);
 465     pTriggerStep->orconf = orconf;
 466   }
 467   sqlite3ExprListDelete(db, pEList);
 468   sqlite3ExprDelete(db, pWhere);
 469   return pTriggerStep;
 470 }
 471
 472 /*
 473 ** Construct a trigger step that implements a DELETE statement and return
 474 ** a pointer to that trigger step.  The parser calls this routine when it
 475 ** sees a DELETE statement inside the body of a CREATE TRIGGER.
 476 */
 477 TriggerStep *sqlite3TriggerDeleteStep(
 478   sqlite3 *db,            /* Database connection */
 479   Token *pTableName,      /* The table from which rows are deleted */
 480   Expr *pWhere,           /* The WHERE clause */
 481   const char *zStart,     /* Start of SQL text */
 482   const char *zEnd        /* End of SQL text */
 483 ){
 484   TriggerStep *pTriggerStep;
 485
 486   pTriggerStep = triggerStepAllocate(db, TK_DELETE, pTableName, zStart, zEnd);
 487   if( pTriggerStep ){
 488     pTriggerStep->pWhere = sqlite3ExprDup(db, pWhere, EXPRDUP_REDUCE);
 489     pTriggerStep->orconf = OE_Default;
 490   }
 491   sqlite3ExprDelete(db, pWhere);
 492   return pTriggerStep;
 493 }
 494
 495 /*
 496 ** Recursively delete a Trigger structure
 497 */
 498 void sqlite3DeleteTrigger(sqlite3 *db, Trigger *pTrigger){
 499   if( pTrigger==0 ) return;
 500   sqlite3DeleteTriggerStep(db, pTrigger->step_list);
 501   sqlite3DbFree(db, pTrigger->zName);
 502   sqlite3DbFree(db, pTrigger->table);
 503   sqlite3ExprDelete(db, pTrigger->pWhen);
 504   sqlite3IdListDelete(db, pTrigger->pColumns);
 505   sqlite3DbFree(db, pTrigger);
 506 }
 507
 508 /*
 509 ** This function is called to drop a trigger from the database schema.
 510 **
 511 ** This may be called directly from the parser and therefore identifies
 512 ** the trigger by name.  The sqlite3DropTriggerPtr() routine does the
 513 ** same job as this routine except it takes a pointer to the trigger
 514 ** instead of the trigger name.
 515 **/
 516 void sqlite3DropTrigger(Parse *pParse, SrcList *pName, int noErr){
 517   Trigger *pTrigger = 0;
 518   int i;
 519   const char *zDb;
 520   const char *zName;
 521   sqlite3 *db = pParse->db;
 522
 523   if( db->mallocFailed ) goto drop_trigger_cleanup;
 524   if( SQLITE_OK!=sqlite3ReadSchema(pParse) ){
 525     goto drop_trigger_cleanup;
 526   }
 527
 528   assert( pName->nSrc==1 );
 529   zDb = pName->a[0].zDatabase;
 530   zName = pName->a[0].zName;
 531   assert( zDb!=0 || sqlite3BtreeHoldsAllMutexes(db) );
 532   for(i=OMIT_TEMPDB; i<db->nDb; i++){
 533     int j = (i<2) ? i^1 : i;  /* Search TEMP before MAIN */
 534     if( zDb && sqlite3StrICmp(db->aDb[j].zDbSName, zDb) ) continue;
 535     assert( sqlite3SchemaMutexHeld(db, j, 0) );
 536     pTrigger = sqlite3HashFind(&(db->aDb[j].pSchema->trigHash), zName);
 537     if( pTrigger ) break;
 538   }
 539   if( !pTrigger ){
 540     if( !noErr ){
 541       sqlite3ErrorMsg(pParse, "no such trigger: %S", pName, 0);
 542     }else{
 543       sqlite3CodeVerifyNamedSchema(pParse, zDb);
 544     }
 545     pParse->checkSchema = 1;
 546     goto drop_trigger_cleanup;
 547   }
 548   sqlite3DropTriggerPtr(pParse, pTrigger);
 549
 550 drop_trigger_cleanup:
 551   sqlite3SrcListDelete(db, pName);
 552 }
 553
 554 /*
 555 ** Return a pointer to the Table structure for the table that a trigger
 556 ** is set on.
 557 */
 558 static Table *tableOfTrigger(Trigger *pTrigger){
 559   return sqlite3HashFind(&pTrigger->pTabSchema->tblHash, pTrigger->table);
 560 }
 561
 562
 563 /*
 564 ** Drop a trigger given a pointer to that trigger.
 565 */
 566 void sqlite3DropTriggerPtr(Parse *pParse, Trigger *pTrigger){
 567   Table   *pTable;
 568   Vdbe *v;
 569   sqlite3 *db = pParse->db;
 570   int iDb;
 571
 572   iDb = sqlite3SchemaToIndex(pParse->db, pTrigger->pSchema);
 573   assert( iDb>=0 && iDb<db->nDb );
 574   pTable = tableOfTrigger(pTrigger);
 575   assert( pTable );
 576   assert( pTable->pSchema==pTrigger->pSchema || iDb==1 );
 577 #ifndef SQLITE_OMIT_AUTHORIZATION
 578   {
 579     int code = SQLITE_DROP_TRIGGER;
 580     const char *zDb = db->aDb[iDb].zDbSName;
 581     const char *zTab = SCHEMA_TABLE(iDb);
 582     if( iDb==1 ) code = SQLITE_DROP_TEMP_TRIGGER;
 583     if( sqlite3AuthCheck(pParse, code, pTrigger->zName, pTable->zName, zDb) ||
 584       sqlite3AuthCheck(pParse, SQLITE_DELETE, zTab, 0, zDb) ){
 585       return;
 586     }
 587   }
 588 #endif
 589
 590   /* Generate code to destroy the database record of the trigger.
 591   */
 592   assert( pTable!=0 );
 593   if( (v = sqlite3GetVdbe(pParse))!=0 ){
 594     sqlite3NestedParse(pParse,
 595        "DELETE FROM %Q.%s WHERE name=%Q AND type='trigger'",
 596        db->aDb[iDb].zDbSName, MASTER_NAME, pTrigger->zName
 597     );
 598     sqlite3ChangeCookie(pParse, iDb);
 599     sqlite3VdbeAddOp4(v, OP_DropTrigger, iDb, 0, 0, pTrigger->zName, 0);
 600   }
 601 }
 602
 603 /*
 604 ** Remove a trigger from the hash tables of the sqlite* pointer.
 605 */
 606 void sqlite3UnlinkAndDeleteTrigger(sqlite3 *db, int iDb, const char *zName){
 607   Trigger *pTrigger;
 608   Hash *pHash;
 609
 610   assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
 611   pHash = &(db->aDb[iDb].pSchema->trigHash);
 612   pTrigger = sqlite3HashInsert(pHash, zName, 0);
 613   if( ALWAYS(pTrigger) ){
 614     if( pTrigger->pSchema==pTrigger->pTabSchema ){
 615       Table *pTab = tableOfTrigger(pTrigger);
 616       Trigger **pp;
 617       for(pp=&pTab->pTrigger; *pp!=pTrigger; pp=&((*pp)->pNext));
 618       *pp = (*pp)->pNext;
 619     }
 620     sqlite3DeleteTrigger(db, pTrigger);
 621     db->mDbFlags |= DBFLAG_SchemaChange;
 622   }
 623 }
 624
 625 /*
 626 ** pEList is the SET clause of an UPDATE statement.  Each entry
 627 ** in pEList is of the format <id>=<expr>.  If any of the entries
 628 ** in pEList have an <id> which matches an identifier in pIdList,
 629 ** then return TRUE.  If pIdList==NULL, then it is considered a
 630 ** wildcard that matches anything.  Likewise if pEList==NULL then
 631 ** it matches anything so always return true.  Return false only
 632 ** if there is no match.
 633 */
 634 static int checkColumnOverlap(IdList *pIdList, ExprList *pEList){
 635   int e;
 636   if( pIdList==0 || NEVER(pEList==0) ) return 1;
 637   for(e=0; e<pEList->nExpr; e++){
 638     if( sqlite3IdListIndex(pIdList, pEList->a[e].zName)>=0 ) return 1;
 639   }
 640   return 0;
 641 }
 642
 643 /*
 644 ** Return a list of all triggers on table pTab if there exists at least
 645 ** one trigger that must be fired when an operation of type 'op' is
 646 ** performed on the table, and, if that operation is an UPDATE, if at
 647 ** least one of the columns in pChanges is being modified.
 648 */
 649 Trigger *sqlite3TriggersExist(
 650   Parse *pParse,          /* Parse context */
 651   Table *pTab,            /* The table the contains the triggers */
 652   int op,                 /* one of TK_DELETE, TK_INSERT, TK_UPDATE */
 653   ExprList *pChanges,     /* Columns that change in an UPDATE statement */
 654   int *pMask              /* OUT: Mask of TRIGGER_BEFORE|TRIGGER_AFTER */
 655 ){
 656   int mask = 0;
 657   Trigger *pList = 0;
 658   Trigger *p;
 659
 660   if( (pParse->db->flags & SQLITE_EnableTrigger)!=0 ){
 661     pList = sqlite3TriggerList(pParse, pTab);
 662   }
 663   assert( pList==0 || IsVirtual(pTab)==0 );
 664   for(p=pList; p; p=p->pNext){
 665     if( p->op==op && checkColumnOverlap(p->pColumns, pChanges) ){
 666       mask |= p->tr_tm;
 667     }
 668   }
 669   if( pMask ){
 670     *pMask = mask;
 671   }
 672   return (mask ? pList : 0);
 673 }
 674
 675 /*
 676 ** Convert the pStep->zTarget string into a SrcList and return a pointer
 677 ** to that SrcList.
 678 **
 679 ** This routine adds a specific database name, if needed, to the target when
 680 ** forming the SrcList.  This prevents a trigger in one database from
 681 ** referring to a target in another database.  An exception is when the
 682 ** trigger is in TEMP in which case it can refer to any other database it
 683 ** wants.
 684 */
 685 static SrcList *targetSrcList(
 686   Parse *pParse,       /* The parsing context */
 687   TriggerStep *pStep   /* The trigger containing the target token */
 688 ){
 689   sqlite3 *db = pParse->db;
 690   int iDb;             /* Index of the database to use */
 691   SrcList *pSrc;       /* SrcList to be returned */
 692
 693   pSrc = sqlite3SrcListAppend(db, 0, 0, 0);
 694   if( pSrc ){
 695     assert( pSrc->nSrc>0 );
 696     pSrc->a[pSrc->nSrc-1].zName = sqlite3DbStrDup(db, pStep->zTarget);
 697     iDb = sqlite3SchemaToIndex(db, pStep->pTrig->pSchema);
 698     if( iDb==0 || iDb>=2 ){
 699       const char *zDb;
 700       assert( iDb<db->nDb );
 701       zDb = db->aDb[iDb].zDbSName;
 702       pSrc->a[pSrc->nSrc-1].zDatabase =  sqlite3DbStrDup(db, zDb);
 703     }
 704   }
 705   return pSrc;
 706 }
 707
 708 /*
 709 ** Generate VDBE code for the statements inside the body of a single
 710 ** trigger.
 711 */
 712 static int codeTriggerProgram(
 713   Parse *pParse,            /* The parser context */
 714   TriggerStep *pStepList,   /* List of statements inside the trigger body */
 715   int orconf                /* Conflict algorithm. (OE_Abort, etc) */
 716 ){
 717   TriggerStep *pStep;
 718   Vdbe *v = pParse->pVdbe;
 719   sqlite3 *db = pParse->db;
 720
 721   assert( pParse->pTriggerTab && pParse->pToplevel );
 722   assert( pStepList );
 723   assert( v!=0 );
 724   for(pStep=pStepList; pStep; pStep=pStep->pNext){
 725     /* Figure out the ON CONFLICT policy that will be used for this step
 726     ** of the trigger program. If the statement that caused this trigger
 727     ** to fire had an explicit ON CONFLICT, then use it. Otherwise, use
 728     ** the ON CONFLICT policy that was specified as part of the trigger
 729     ** step statement. Example:
 730     **
 731     **   CREATE TRIGGER AFTER INSERT ON t1 BEGIN;
 732     **     INSERT OR REPLACE INTO t2 VALUES(new.a, new.b);
 733     **   END;
 734     **
 735     **   INSERT INTO t1 ... ;            -- insert into t2 uses REPLACE policy
 736     **   INSERT OR IGNORE INTO t1 ... ;  -- insert into t2 uses IGNORE policy
 737     */
 738     pParse->eOrconf = (orconf==OE_Default)?pStep->orconf:(u8)orconf;
 739     assert( pParse->okConstFactor==0 );
 740
 741 #ifndef SQLITE_OMIT_TRACE
 742     if( pStep->zSpan ){
 743       sqlite3VdbeAddOp4(v, OP_Trace, 0x7fffffff, 1, 0,
 744                         sqlite3MPrintf(db, "-- %s", pStep->zSpan),
 745                         P4_DYNAMIC);
 746     }
 747 #endif
 748
 749     switch( pStep->op ){
 750       case TK_UPDATE: {
 751         sqlite3Update(pParse,
 752           targetSrcList(pParse, pStep),
 753           sqlite3ExprListDup(db, pStep->pExprList, 0),
 754           sqlite3ExprDup(db, pStep->pWhere, 0),
 755           pParse->eOrconf, 0, 0, 0
 756         );
 757         break;
 758       }
 759       case TK_INSERT: {
 760         sqlite3Insert(pParse,
 761           targetSrcList(pParse, pStep),
 762           sqlite3SelectDup(db, pStep->pSelect, 0),
 763           sqlite3IdListDup(db, pStep->pIdList),
 764           pParse->eOrconf,
 765           sqlite3UpsertDup(db, pStep->pUpsert)
 766         );
 767         break;
 768       }
 769       case TK_DELETE: {
 770         sqlite3DeleteFrom(pParse,
 771           targetSrcList(pParse, pStep),
 772           sqlite3ExprDup(db, pStep->pWhere, 0), 0, 0
 773         );
 774         break;
 775       }
 776       default: assert( pStep->op==TK_SELECT ); {
 777         SelectDest sDest;
 778         Select *pSelect = sqlite3SelectDup(db, pStep->pSelect, 0);
 779         sqlite3SelectDestInit(&sDest, SRT_Discard, 0);
 780         sqlite3Select(pParse, pSelect, &sDest);
 781         sqlite3SelectDelete(db, pSelect);
 782         break;
 783       }
 784     }
 785     if( pStep->op!=TK_SELECT ){
 786       sqlite3VdbeAddOp0(v, OP_ResetCount);
 787     }
 788   }
 789
 790   return 0;
 791 }
 792
 793 #ifdef SQLITE_ENABLE_EXPLAIN_COMMENTS
 794 /*
 795 ** This function is used to add VdbeComment() annotations to a VDBE
 796 ** program. It is not used in production code, only for debugging.
 797 */
 798 static const char *onErrorText(int onError){
 799   switch( onError ){
 800     case OE_Abort:    return "abort";
 801     case OE_Rollback: return "rollback";
 802     case OE_Fail:     return "fail";
 803     case OE_Replace:  return "replace";
 804     case OE_Ignore:   return "ignore";
 805     case OE_Default:  return "default";
 806   }
 807   return "n/a";
 808 }
 809 #endif
 810
 811 /*
 812 ** Parse context structure pFrom has just been used to create a sub-vdbe
 813 ** (trigger program). If an error has occurred, transfer error information
 814 ** from pFrom to pTo.
 815 */
 816 static void transferParseError(Parse *pTo, Parse *pFrom){
 817   assert( pFrom->zErrMsg==0 || pFrom->nErr );
 818   assert( pTo->zErrMsg==0 || pTo->nErr );
 819   if( pTo->nErr==0 ){
 820     pTo->zErrMsg = pFrom->zErrMsg;
 821     pTo->nErr = pFrom->nErr;
 822     pTo->rc = pFrom->rc;
 823   }else{
 824     sqlite3DbFree(pFrom->db, pFrom->zErrMsg);
 825   }
 826 }
 827
 828 /*
 829 ** Create and populate a new TriggerPrg object with a sub-program
 830 ** implementing trigger pTrigger with ON CONFLICT policy orconf.
 831 */
 832 static TriggerPrg *codeRowTrigger(
 833   Parse *pParse,       /* Current parse context */
 834   Trigger *pTrigger,   /* Trigger to code */
 835   Table *pTab,         /* The table pTrigger is attached to */
 836   int orconf           /* ON CONFLICT policy to code trigger program with */
 837 ){
 838   Parse *pTop = sqlite3ParseToplevel(pParse);
 839   sqlite3 *db = pParse->db;   /* Database handle */
 840   TriggerPrg *pPrg;           /* Value to return */
 841   Expr *pWhen = 0;            /* Duplicate of trigger WHEN expression */
 842   Vdbe *v;                    /* Temporary VM */
 843   NameContext sNC;            /* Name context for sub-vdbe */
 844   SubProgram *pProgram = 0;   /* Sub-vdbe for trigger program */
 845   Parse *pSubParse;           /* Parse context for sub-vdbe */
 846   int iEndTrigger = 0;        /* Label to jump to if WHEN is false */
 847
 848   assert( pTrigger->zName==0 || pTab==tableOfTrigger(pTrigger) );
 849   assert( pTop->pVdbe );
 850
 851   /* Allocate the TriggerPrg and SubProgram objects. To ensure that they
 852   ** are freed if an error occurs, link them into the Parse.pTriggerPrg
 853   ** list of the top-level Parse object sooner rather than later.  */
 854   pPrg = sqlite3DbMallocZero(db, sizeof(TriggerPrg));
 855   if( !pPrg ) return 0;
 856   pPrg->pNext = pTop->pTriggerPrg;
 857   pTop->pTriggerPrg = pPrg;
 858   pPrg->pProgram = pProgram = sqlite3DbMallocZero(db, sizeof(SubProgram));
 859   if( !pProgram ) return 0;
 860   sqlite3VdbeLinkSubProgram(pTop->pVdbe, pProgram);
 861   pPrg->pTrigger = pTrigger;
 862   pPrg->orconf = orconf;
 863   pPrg->aColmask[0] = 0xffffffff;
 864   pPrg->aColmask[1] = 0xffffffff;
 865
 866   /* Allocate and populate a new Parse context to use for coding the
 867   ** trigger sub-program.  */
 868   pSubParse = sqlite3StackAllocZero(db, sizeof(Parse));
 869   if( !pSubParse ) return 0;
 870   memset(&sNC, 0, sizeof(sNC));
 871   sNC.pParse = pSubParse;
 872   pSubParse->db = db;
 873   pSubParse->pTriggerTab = pTab;
 874   pSubParse->pToplevel = pTop;
 875   pSubParse->zAuthContext = pTrigger->zName;
 876   pSubParse->eTriggerOp = pTrigger->op;
 877   pSubParse->nQueryLoop = pParse->nQueryLoop;
 878
 879   v = sqlite3GetVdbe(pSubParse);
 880   if( v ){
 881     VdbeComment((v, "Start: %s.%s (%s %s%s%s ON %s)",
 882       pTrigger->zName, onErrorText(orconf),
 883       (pTrigger->tr_tm==TRIGGER_BEFORE ? "BEFORE" : "AFTER"),
 884         (pTrigger->op==TK_UPDATE ? "UPDATE" : ""),
 885         (pTrigger->op==TK_INSERT ? "INSERT" : ""),
 886         (pTrigger->op==TK_DELETE ? "DELETE" : ""),
 887       pTab->zName
 888     ));
 889 #ifndef SQLITE_OMIT_TRACE
 890     if( pTrigger->zName ){
 891       sqlite3VdbeChangeP4(v, -1,
 892         sqlite3MPrintf(db, "-- TRIGGER %s", pTrigger->zName), P4_DYNAMIC
 893       );
 894     }
 895 #endif
 896
 897     /* If one was specified, code the WHEN clause. If it evaluates to false
 898     ** (or NULL) the sub-vdbe is immediately halted by jumping to the
 899     ** OP_Halt inserted at the end of the program.  */
 900     if( pTrigger->pWhen ){
 901       pWhen = sqlite3ExprDup(db, pTrigger->pWhen, 0);
 902       if( SQLITE_OK==sqlite3ResolveExprNames(&sNC, pWhen)
 903        && db->mallocFailed==0
 904       ){
 905         iEndTrigger = sqlite3VdbeMakeLabel(v);
 906         sqlite3ExprIfFalse(pSubParse, pWhen, iEndTrigger, SQLITE_JUMPIFNULL);
 907       }
 908       sqlite3ExprDelete(db, pWhen);
 909     }
 910
 911     /* Code the trigger program into the sub-vdbe. */
 912     codeTriggerProgram(pSubParse, pTrigger->step_list, orconf);
 913
 914     /* Insert an OP_Halt at the end of the sub-program. */
 915     if( iEndTrigger ){
 916       sqlite3VdbeResolveLabel(v, iEndTrigger);
 917     }
 918     sqlite3VdbeAddOp0(v, OP_Halt);
 919     VdbeComment((v, "End: %s.%s", pTrigger->zName, onErrorText(orconf)));
 920
 921     transferParseError(pParse, pSubParse);
 922     if( db->mallocFailed==0 && pParse->nErr==0 ){
 923       pProgram->aOp = sqlite3VdbeTakeOpArray(v, &pProgram->nOp, &pTop->nMaxArg);
 924     }
 925     pProgram->nMem = pSubParse->nMem;
 926     pProgram->nCsr = pSubParse->nTab;
 927     pProgram->token = (void *)pTrigger;
 928     pPrg->aColmask[0] = pSubParse->oldmask;
 929     pPrg->aColmask[1] = pSubParse->newmask;
 930     sqlite3VdbeDelete(v);
 931   }
 932
 933   assert( !pSubParse->pAinc       && !pSubParse->pZombieTab );
 934   assert( !pSubParse->pTriggerPrg && !pSubParse->nMaxArg );
 935   sqlite3ParserReset(pSubParse);
 936   sqlite3StackFree(db, pSubParse);
 937
 938   return pPrg;
 939 }
 940
 941 /*
 942 ** Return a pointer to a TriggerPrg object containing the sub-program for
 943 ** trigger pTrigger with default ON CONFLICT algorithm orconf. If no such
 944 ** TriggerPrg object exists, a new object is allocated and populated before
 945 ** being returned.
 946 */
 947 static TriggerPrg *getRowTrigger(
 948   Parse *pParse,       /* Current parse context */
 949   Trigger *pTrigger,   /* Trigger to code */
 950   Table *pTab,         /* The table trigger pTrigger is attached to */
 951   int orconf           /* ON CONFLICT algorithm. */
 952 ){
 953   Parse *pRoot = sqlite3ParseToplevel(pParse);
 954   TriggerPrg *pPrg;
 955
 956   assert( pTrigger->zName==0 || pTab==tableOfTrigger(pTrigger) );
 957
 958   /* It may be that this trigger has already been coded (or is in the
 959   ** process of being coded). If this is the case, then an entry with
 960   ** a matching TriggerPrg.pTrigger field will be present somewhere
 961   ** in the Parse.pTriggerPrg list. Search for such an entry.  */
 962   for(pPrg=pRoot->pTriggerPrg;
 963       pPrg && (pPrg->pTrigger!=pTrigger || pPrg->orconf!=orconf);
 964       pPrg=pPrg->pNext
 965   );
 966
 967   /* If an existing TriggerPrg could not be located, create a new one. */
 968   if( !pPrg ){
 969     pPrg = codeRowTrigger(pParse, pTrigger, pTab, orconf);
 970   }
 971
 972   return pPrg;
 973 }
 974
 975 /*
 976 ** Generate code for the trigger program associated with trigger p on
 977 ** table pTab. The reg, orconf and ignoreJump parameters passed to this
 978 ** function are the same as those described in the header function for
 979 ** sqlite3CodeRowTrigger()
 980 */
 981 void sqlite3CodeRowTriggerDirect(
 982   Parse *pParse,       /* Parse context */
 983   Trigger *p,          /* Trigger to code */
 984   Table *pTab,         /* The table to code triggers from */
 985   int reg,             /* Reg array containing OLD.* and NEW.* values */
 986   int orconf,          /* ON CONFLICT policy */
 987   int ignoreJump       /* Instruction to jump to for RAISE(IGNORE) */
 988 ){
 989   Vdbe *v = sqlite3GetVdbe(pParse); /* Main VM */
 990   TriggerPrg *pPrg;
 991   pPrg = getRowTrigger(pParse, p, pTab, orconf);
 992   assert( pPrg || pParse->nErr || pParse->db->mallocFailed );
 993
 994   /* Code the OP_Program opcode in the parent VDBE. P4 of the OP_Program
 995   ** is a pointer to the sub-vdbe containing the trigger program.  */
 996   if( pPrg ){
 997     int bRecursive = (p->zName && 0==(pParse->db->flags&SQLITE_RecTriggers));
 998
 999     sqlite3VdbeAddOp4(v, OP_Program, reg, ignoreJump, ++pParse->nMem,
1000                       (const char *)pPrg->pProgram, P4_SUBPROGRAM);
1001     VdbeComment(
1002         (v, "Call: %s.%s", (p->zName?p->zName:"fkey"), onErrorText(orconf)));
1003
1004     /* Set the P5 operand of the OP_Program instruction to non-zero if
1005     ** recursive invocation of this trigger program is disallowed. Recursive
1006     ** invocation is disallowed if (a) the sub-program is really a trigger,
1007     ** not a foreign key action, and (b) the flag to enable recursive triggers
1008     ** is clear.  */
1009     sqlite3VdbeChangeP5(v, (u8)bRecursive);
1010   }
1011 }
1012
1013 /*
1014 ** This is called to code the required FOR EACH ROW triggers for an operation
1015 ** on table pTab. The operation to code triggers for (INSERT, UPDATE or DELETE)
1016 ** is given by the op parameter. The tr_tm parameter determines whether the
1017 ** BEFORE or AFTER triggers are coded. If the operation is an UPDATE, then
1018 ** parameter pChanges is passed the list of columns being modified.
1019 **
1020 ** If there are no triggers that fire at the specified time for the specified
1021 ** operation on pTab, this function is a no-op.
1022 **
1023 ** The reg argument is the address of the first in an array of registers
1024 ** that contain the values substituted for the new.* and old.* references
1025 ** in the trigger program. If N is the number of columns in table pTab
1026 ** (a copy of pTab->nCol), then registers are populated as follows:
1027 **
1028 **   Register       Contains
1029 **   ------------------------------------------------------
1030 **   reg+0          OLD.rowid
1031 **   reg+1          OLD.* value of left-most column of pTab
1032 **   ...            ...
1033 **   reg+N          OLD.* value of right-most column of pTab
1034 **   reg+N+1        NEW.rowid
1035 **   reg+N+2        OLD.* value of left-most column of pTab
1036 **   ...            ...
1037 **   reg+N+N+1      NEW.* value of right-most column of pTab
1038 **
1039 ** For ON DELETE triggers, the registers containing the NEW.* values will
1040 ** never be accessed by the trigger program, so they are not allocated or
1041 ** populated by the caller (there is no data to populate them with anyway).
1042 ** Similarly, for ON INSERT triggers the values stored in the OLD.* registers
1043 ** are never accessed, and so are not allocated by the caller. So, for an
1044 ** ON INSERT trigger, the value passed to this function as parameter reg
1045 ** is not a readable register, although registers (reg+N) through
1046 ** (reg+N+N+1) are.
1047 **
1048 ** Parameter orconf is the default conflict resolution algorithm for the
1049 ** trigger program to use (REPLACE, IGNORE etc.). Parameter ignoreJump
1050 ** is the instruction that control should jump to if a trigger program
1051 ** raises an IGNORE exception.
1052 */
1053 void sqlite3CodeRowTrigger(
1054   Parse *pParse,       /* Parse context */
1055   Trigger *pTrigger,   /* List of triggers on table pTab */
1056   int op,              /* One of TK_UPDATE, TK_INSERT, TK_DELETE */
1057   ExprList *pChanges,  /* Changes list for any UPDATE OF triggers */
1058   int tr_tm,           /* One of TRIGGER_BEFORE, TRIGGER_AFTER */
1059   Table *pTab,         /* The table to code triggers from */
1060   int reg,             /* The first in an array of registers (see above) */
1061   int orconf,          /* ON CONFLICT policy */
1062   int ignoreJump       /* Instruction to jump to for RAISE(IGNORE) */
1063 ){
1064   Trigger *p;          /* Used to iterate through pTrigger list */
1065
1066   assert( op==TK_UPDATE || op==TK_INSERT || op==TK_DELETE );
1067   assert( tr_tm==TRIGGER_BEFORE || tr_tm==TRIGGER_AFTER );
1068   assert( (op==TK_UPDATE)==(pChanges!=0) );
1069
1070   for(p=pTrigger; p; p=p->pNext){
1071
1072     /* Sanity checking:  The schema for the trigger and for the table are
1073     ** always defined.  The trigger must be in the same schema as the table
1074     ** or else it must be a TEMP trigger. */
1075     assert( p->pSchema!=0 );
1076     assert( p->pTabSchema!=0 );
1077     assert( p->pSchema==p->pTabSchema
1078          || p->pSchema==pParse->db->aDb[1].pSchema );
1079
1080     /* Determine whether we should code this trigger */
1081     if( p->op==op
1082      && p->tr_tm==tr_tm
1083      && checkColumnOverlap(p->pColumns, pChanges)
1084     ){
1085       sqlite3CodeRowTriggerDirect(pParse, p, pTab, reg, orconf, ignoreJump);
1086     }
1087   }
1088 }
1089
1090 /*
1091 ** Triggers may access values stored in the old.* or new.* pseudo-table.
1092 ** This function returns a 32-bit bitmask indicating which columns of the
1093 ** old.* or new.* tables actually are used by triggers. This information
1094 ** may be used by the caller, for example, to avoid having to load the entire
1095 ** old.* record into memory when executing an UPDATE or DELETE command.
1096 **
1097 ** Bit 0 of the returned mask is set if the left-most column of the
1098 ** table may be accessed using an [old|new].<col> reference. Bit 1 is set if
1099 ** the second leftmost column value is required, and so on. If there
1100 ** are more than 32 columns in the table, and at least one of the columns
1101 ** with an index greater than 32 may be accessed, 0xffffffff is returned.
1102 **
1103 ** It is not possible to determine if the old.rowid or new.rowid column is
1104 ** accessed by triggers. The caller must always assume that it is.
1105 **
1106 ** Parameter isNew must be either 1 or 0. If it is 0, then the mask returned
1107 ** applies to the old.* table. If 1, the new.* table.
1108 **
1109 ** Parameter tr_tm must be a mask with one or both of the TRIGGER_BEFORE
1110 ** and TRIGGER_AFTER bits set. Values accessed by BEFORE triggers are only
1111 ** included in the returned mask if the TRIGGER_BEFORE bit is set in the
1112 ** tr_tm parameter. Similarly, values accessed by AFTER triggers are only
1113 ** included in the returned mask if the TRIGGER_AFTER bit is set in tr_tm.
1114 */
1115 u32 sqlite3TriggerColmask(
1116   Parse *pParse,       /* Parse context */
1117   Trigger *pTrigger,   /* List of triggers on table pTab */
1118   ExprList *pChanges,  /* Changes list for any UPDATE OF triggers */
1119   int isNew,           /* 1 for new.* ref mask, 0 for old.* ref mask */
1120   int tr_tm,           /* Mask of TRIGGER_BEFORE|TRIGGER_AFTER */
1121   Table *pTab,         /* The table to code triggers from */
1122   int orconf           /* Default ON CONFLICT policy for trigger steps */
1123 ){
1124   const int op = pChanges ? TK_UPDATE : TK_DELETE;
1125   u32 mask = 0;
1126   Trigger *p;
1127
1128   assert( isNew==1 || isNew==0 );
1129   for(p=pTrigger; p; p=p->pNext){
1130     if( p->op==op && (tr_tm&p->tr_tm)
1131      && checkColumnOverlap(p->pColumns,pChanges)
1132     ){
1133       TriggerPrg *pPrg;
1134       pPrg = getRowTrigger(pParse, p, pTab, orconf);
1135       if( pPrg ){
1136         mask |= pPrg->aColmask[isNew];
1137       }
1138     }
1139   }
1140
1141   return mask;
1142 }
1143
1144 #endif /* !defined(SQLITE_OMIT_TRIGGER) */