SQLite

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle DELETE FROM statements.
**
** $Id: delete.c,v 1.91 2004/11/23 01:47:30 drh Exp $
*/
#include "sqliteInt.h"

/*
** Look up every table that is named in pSrc.  If any table is not found,
** add an error message to pParse->zErrMsg and return NULL.  If all tables
** are found, return a pointer to the last table.

  int iCur;              /* VDBE Cursor number for pTab */
  sqlite3 *db;           /* Main database structure */
  AuthContext sContext;  /* Authorization context */
  int oldIdx = -1;       /* Cursor for the OLD table of AFTER triggers */

#ifndef SQLITE_OMIT_TRIGGER
  int isView;                  /* True if attempting to delete from a view */
  int row_triggers_exist = 0;  /* True if any triggers exist */
  int before_triggers;         /* True if there are BEFORE triggers */
  int after_triggers;          /* True if there are AFTER triggers */
#endif

  sContext.pParse = 0;
  if( pParse->nErr || sqlite3_malloc_failed ){
    pTabList = 0;
    goto delete_from_cleanup;
  }

  pTab = sqlite3SrcListLookup(pParse, pTabList);
  if( pTab==0 )  goto delete_from_cleanup;

  /* Figure out if we have any triggers and if the table being
  ** deleted from is a view
  */
#ifndef SQLITE_OMIT_TRIGGER
  before_triggers = sqlite3TriggersExist(pParse, pTab->pTrigger, 
                         TK_DELETE, TK_BEFORE, TK_ROW, 0);
  after_triggers = sqlite3TriggersExist(pParse, pTab->pTrigger, 
                         TK_DELETE, TK_AFTER, TK_ROW, 0);
  row_triggers_exist = before_triggers || after_triggers;
  isView = pTab->pSelect!=0;
#else
# define before_triggers 0
# define after_triggers 0
# define row_triggers_exist 0
# define isView 0
#endif
#ifdef SQLITE_OMIT_VIEW
# undef isView
# define isView 0
#endif

  if( sqlite3IsReadOnly(pParse, pTab, before_triggers) ){
    goto delete_from_cleanup;
  }
  assert( pTab->iDb<db->nDb );
  zDb = db->aDb[pTab->iDb].zName;
  if( sqlite3AuthCheck(pParse, SQLITE_DELETE, pTab->zName, 0, zDb) ){
    goto delete_from_cleanup;
  }

  /* If pTab is really a view, make sure it has been initialized.
  */
  if( isView && sqlite3ViewGetColumnNames(pParse, pTab) ){
    goto delete_from_cleanup;
  }

  /* Allocate a cursor used to store the old.* data for a trigger.
  */
  if( row_triggers_exist ){ 
    oldIdx = pParse->nTab++;
  }

  /* Resolve the column names in all the expressions.
  */
  assert( pTabList->nSrc==1 );
  iCur = pTabList->a[0].iCursor = pParse->nTab++;

  /* Begin generating code.
  */
  v = sqlite3GetVdbe(pParse);
  if( v==0 ){
    goto delete_from_cleanup;
  }
  if( pParse->nested==0 ) sqlite3VdbeCountChanges(v);
  sqlite3BeginWriteOperation(pParse, row_triggers_exist, pTab->iDb);

  /* If we are trying to delete from a view, construct that view into
  ** a temporary table.
  */
  if( isView ){
    Select *pView = sqlite3SelectDup(pTab->pSelect);
    sqlite3Select(pParse, pView, SRT_TempTable, iCur, 0, 0, 0, 0);

    sqlite3VdbeAddOp(v, OP_Integer, 0, 0);
  }

  /* Special case: A DELETE without a WHERE clause deletes everything.
  ** It is easier just to erase the whole table.  Note, however, that
  ** this means that the row change count will be incorrect.
  */
  if( pWhere==0 && !row_triggers_exist ){
    if( db->flags & SQLITE_CountRows ){
      /* If counting rows deleted, just count the total number of
      ** entries in the table. */
      int endOfLoop = sqlite3VdbeMakeLabel(v);
      int addr;
      if( !isView ){
        sqlite3OpenTableForReading(v, iCur, pTab);

    /* End the database scan loop.
    */
    sqlite3WhereEnd(pWInfo);

    /* Open the pseudo-table used to store OLD if there are triggers.
    */
    if( row_triggers_exist ){
      sqlite3VdbeAddOp(v, OP_OpenPseudo, oldIdx, 0);
      sqlite3VdbeAddOp(v, OP_SetNumColumns, oldIdx, pTab->nCol);
    }

    /* Delete every item whose key was written to the list during the
    ** database scan.  We have to delete items after the scan is complete
    ** because deleting an item can change the scan order.
    */
    sqlite3VdbeAddOp(v, OP_ListRewind, 0, 0);
    end = sqlite3VdbeMakeLabel(v);

    /* This is the beginning of the delete loop when there are
    ** row triggers.
    */
    if( row_triggers_exist ){
      addr = sqlite3VdbeAddOp(v, OP_ListRead, 0, end);
      sqlite3VdbeAddOp(v, OP_Dup, 0, 0);
      if( !isView ){
        sqlite3OpenTableForReading(v, iCur, pTab);
      }
      sqlite3VdbeAddOp(v, OP_MoveGe, iCur, 0);
      sqlite3VdbeAddOp(v, OP_Recno, iCur, 0);
      sqlite3VdbeAddOp(v, OP_RowData, iCur, 0);
      sqlite3VdbeAddOp(v, OP_PutIntKey, oldIdx, 0);
      if( !isView ){
        sqlite3VdbeAddOp(v, OP_Close, iCur, 0);
      }

      (void)sqlite3CodeRowTrigger(pParse, TK_DELETE, 0, TK_BEFORE, pTab, -1, 
          oldIdx, (pParse->trigStack)?pParse->trigStack->orconf:OE_Default,
	  addr);
    }

    if( !isView ){
      /* Open cursors for the table we are deleting from and all its
      ** indices.  If there are row triggers, this happens inside the
      ** OP_ListRead loop because the cursor have to all be closed
      ** before the trigger fires.  If there are no row triggers, the
      ** cursors are opened only once on the outside the loop.
      */
      sqlite3OpenTableAndIndices(pParse, pTab, iCur, OP_OpenWrite);

      /* This is the beginning of the delete loop when there are no
      ** row triggers */
      if( !row_triggers_exist ){ 
        addr = sqlite3VdbeAddOp(v, OP_ListRead, 0, end);
      }

      /* Delete the row */
      sqlite3GenerateRowDelete(db, v, pTab, iCur, pParse->nested==0);
    }

    /* If there are row triggers, close all cursors then invoke
    ** the AFTER triggers
    */
    if( row_triggers_exist ){
      if( !isView ){
        for(i=1, pIdx=pTab->pIndex; pIdx; i++, pIdx=pIdx->pNext){
          sqlite3VdbeAddOp(v, OP_Close, iCur + i, pIdx->tnum);
        }
        sqlite3VdbeAddOp(v, OP_Close, iCur, 0);
      }
      (void)sqlite3CodeRowTrigger(pParse, TK_DELETE, 0, TK_AFTER, pTab, -1, 
          oldIdx, (pParse->trigStack)?pParse->trigStack->orconf:OE_Default,
	  addr);
    }

    /* End of the delete loop */
    sqlite3VdbeAddOp(v, OP_Goto, 0, addr);
    sqlite3VdbeResolveLabel(v, end);
    sqlite3VdbeAddOp(v, OP_ListReset, 0, 0);

    /* Close the cursors after the loop if there are no row triggers */
    if( !row_triggers_exist ){
      for(i=1, pIdx=pTab->pIndex; pIdx; i++, pIdx=pIdx->pNext){
        sqlite3VdbeAddOp(v, OP_Close, iCur + i, pIdx->tnum);
      }
      sqlite3VdbeAddOp(v, OP_Close, iCur, 0);
    }
  }

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle INSERT statements in SQLite.
**
** $Id: insert.c,v 1.126 2004/11/13 03:48:07 drh Exp $
*/
#include "sqliteInt.h"

/*
** Set P3 of the most recently inserted opcode to a column affinity
** string for index pIdx. A column affinity string has one character
** for each column in the table, according to the affinity of the column:

  int iCntMem = 0;      /* Memory cell used for the row counter */
  int newIdx = -1;      /* Cursor for the NEW table */
  Db *pDb;              /* The database containing table being inserted into */
  int counterMem = 0;   /* Memory cell holding AUTOINCREMENT counter */

#ifndef SQLITE_OMIT_TRIGGER
  int isView;                 /* True if attempting to insert into a view */
  int row_triggers_exist = 0; /* True if there are FOR EACH ROW triggers */
  int before_triggers;        /* True if there are BEFORE triggers */
  int after_triggers;         /* True if there are AFTER triggers */
#endif

#ifndef SQLITE_OMIT_AUTOINCREMENT
  int counterRowid;     /* Memory cell holding rowid of autoinc counter */
#endif

  if( pParse->nErr || sqlite3_malloc_failed ) goto insert_cleanup;

    goto insert_cleanup;
  }

  /* Figure out if we have any triggers and if the table being
  ** inserted into is a view
  */
#ifndef SQLITE_OMIT_TRIGGER
  before_triggers = sqlite3TriggersExist(pParse, pTab->pTrigger, 
                         TK_INSERT, TK_BEFORE, TK_ROW, 0);
  after_triggers = sqlite3TriggersExist(pParse, pTab->pTrigger, 
                         TK_INSERT, TK_AFTER, TK_ROW, 0);
  row_triggers_exist = before_triggers || after_triggers;
  isView = pTab->pSelect!=0;
#else
# define before_triggers 0
# define after_triggers 0
# define row_triggers_exist 0
# define isView 0
#endif
#ifdef SQLITE_OMIT_VIEW
# undef isView
# define isView 0
#endif

  /* Ensure that:
  *  (a) the table is not read-only, 
  *  (b) that if it is a view then ON INSERT triggers exist
  */
  if( sqlite3IsReadOnly(pParse, pTab, before_triggers) ){
    goto insert_cleanup;
  }
  if( pTab==0 ) goto insert_cleanup;

  /* If pTab is really a view, make sure it has been initialized.
  */
  if( isView && sqlite3ViewGetColumnNames(pParse, pTab) ){

  }

  /* Allocate a VDBE
  */
  v = sqlite3GetVdbe(pParse);
  if( v==0 ) goto insert_cleanup;
  if( pParse->nested==0 ) sqlite3VdbeCountChanges(v);
  sqlite3BeginWriteOperation(pParse, pSelect || row_triggers_exist, pTab->iDb);

  /* if there are row triggers, allocate a temp table for new.* references. */
  if( row_triggers_exist ){
    newIdx = pParse->nTab++;
  }

#ifndef SQLITE_OMIT_AUTOINCREMENT
  /* If this is an AUTOINCREMENT table, look up the sequence number in the
  ** sqlite_sequence table and store it in memory cell counterMem.  Also
  ** remember the rowid of the sqlite_sequence table entry in memory cell

    ** should be written into a temporary table.  Set to FALSE if each
    ** row of the SELECT can be written directly into the result table.
    **
    ** A temp table must be used if the table being updated is also one
    ** of the tables being read by the SELECT statement.  Also use a 
    ** temp table in the case of row triggers.
    */
    if( row_triggers_exist ){
      useTempTable = 1;
    }else{
      int addr = 0;
      useTempTable = 0;
      while( useTempTable==0 ){
        VdbeOp *pOp;
        addr = sqlite3VdbeFindOp(v, addr, OP_OpenRead, pTab->tnum);

  */
  if( pColumn==0 ){
    keyColumn = pTab->iPKey;
  }

  /* Open the temp table for FOR EACH ROW triggers
  */
  if( row_triggers_exist ){
    sqlite3VdbeAddOp(v, OP_OpenPseudo, newIdx, 0);
    sqlite3VdbeAddOp(v, OP_SetNumColumns, newIdx, pTab->nCol);
  }
    
  /* Initialize the count of rows to be inserted
  */
  if( db->flags & SQLITE_CountRows ){
    iCntMem = pParse->nMem++;
    sqlite3VdbeAddOp(v, OP_Integer, 0, 0);
    sqlite3VdbeAddOp(v, OP_MemStore, iCntMem, 1);
  }

  /* Open tables and indices if there are no row triggers */
  if( !row_triggers_exist ){
    base = pParse->nTab;
    sqlite3OpenTableAndIndices(pParse, pTab, base, OP_OpenWrite);
  }

  /* If the data source is a temporary table, then we have to create
  ** a loop because there might be multiple rows of data.  If the data
  ** source is a subroutine call from the SELECT statement, then we need

    sqlite3VdbeAddOp(v, OP_Goto, 0, iSelectLoop);
    sqlite3VdbeResolveLabel(v, iInsertBlock);
  }

  /* Run the BEFORE and INSTEAD OF triggers, if there are any
  */
  endOfLoop = sqlite3VdbeMakeLabel(v);
  if( before_triggers ){

    /* build the NEW.* reference row.  Note that if there is an INTEGER
    ** PRIMARY KEY into which a NULL is being inserted, that NULL will be
    ** translated into a unique ID for the row.  But on a BEFORE trigger,
    ** we do not know what the unique ID will be (because the insert has
    ** not happened yet) so we substitute a rowid of -1
    */

    */
    if( !isView ){
      sqlite3TableAffinityStr(v, pTab);
    }
    sqlite3VdbeAddOp(v, OP_PutIntKey, newIdx, 0);

    /* Fire BEFORE or INSTEAD OF triggers */
    if( sqlite3CodeRowTrigger(pParse, TK_INSERT, 0, TK_BEFORE, pTab, 
        newIdx, -1, onError, endOfLoop) ){
      goto insert_cleanup;
    }
  }

  /* If any triggers exists, the opening of tables and indices is deferred
  ** until now.
  */
  if( row_triggers_exist && !isView ){
    base = pParse->nTab;
    sqlite3OpenTableAndIndices(pParse, pTab, base, OP_OpenWrite);
  }

  /* Push the record number for the new entry onto the stack.  The
  ** record number is a randomly generate integer created by NewRecno
  ** except when the table has an INTEGER PRIMARY KEY column, in which

    /* Generate code to check constraints and generate index keys and
    ** do the insertion.
    */
    sqlite3GenerateConstraintChecks(pParse, pTab, base, 0, keyColumn>=0,
                                   0, onError, endOfLoop);
    sqlite3CompleteInsertion(pParse, pTab, base, 0,0,0,
                            after_triggers ? newIdx : -1);
  }

  /* Update the count of rows that are inserted
  */
  if( (db->flags & SQLITE_CountRows)!=0 ){
    sqlite3VdbeAddOp(v, OP_MemIncr, iCntMem, 0);
  }

  if( row_triggers_exist ){
    /* Close all tables opened */
    if( !isView ){
      sqlite3VdbeAddOp(v, OP_Close, base, 0);
      for(idx=1, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, idx++){
        sqlite3VdbeAddOp(v, OP_Close, idx+base, 0);
      }
    }

    /* Code AFTER triggers */
    if( sqlite3CodeRowTrigger(pParse, TK_INSERT, 0, TK_AFTER, pTab, newIdx, -1, 
          onError, endOfLoop) ){
      goto insert_cleanup;
    }
  }

  /* The bottom of the loop, if the data source is a SELECT statement
  */
  sqlite3VdbeResolveLabel(v, endOfLoop);
  if( useTempTable ){
    sqlite3VdbeAddOp(v, OP_Next, srcTab, iCont);
    sqlite3VdbeResolveLabel(v, iBreak);
    sqlite3VdbeAddOp(v, OP_Close, srcTab, 0);
  }else if( pSelect ){
    sqlite3VdbeAddOp(v, OP_Pop, nColumn, 0);
    sqlite3VdbeAddOp(v, OP_Return, 0, 0);
    sqlite3VdbeResolveLabel(v, iCleanup);
  }

  if( !row_triggers_exist ){
    /* Close all tables opened */
    sqlite3VdbeAddOp(v, OP_Close, base, 0);
    for(idx=1, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, idx++){
      sqlite3VdbeAddOp(v, OP_Close, idx+base, 0);
    }
  }

/*
** 2001 September 15
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** Internal interface definitions for SQLite.
**
** @(#) $Id: sqliteInt.h,v 1.344 2004/11/23 01:47:30 drh Exp $
*/
#ifndef _SQLITEINT_H_
#define _SQLITEINT_H_

/*
** These #defines should enable >2GB file support on Posix if the
** underlying operating system supports it.  If the OS lacks

 */
struct Trigger {
  char *name;             /* The name of the trigger                        */
  char *table;            /* The table or view to which the trigger applies */
  u8 iDb;                 /* Database containing this trigger               */
  u8 iTabDb;              /* Database containing Trigger.table              */
  u8 op;                  /* One of TK_DELETE, TK_UPDATE, TK_INSERT         */
  u8 tr_tm;               /* One of TK_BEFORE, TK_AFTER */
  Expr *pWhen;            /* The WHEN clause of the expresion (may be NULL) */
  IdList *pColumns;       /* If this is an UPDATE OF <column-list> trigger,
                             the <column-list> is stored here */
  int foreach;            /* One of TK_ROW or TK_STATEMENT */
  Token nameToken;        /* Token containing zName. Use during parsing only */

  TriggerStep *step_list; /* Link list of trigger program steps             */
  Trigger *pNext;         /* Next trigger associated with the table */
};











/*
 * An instance of struct TriggerStep is used to store a single SQL statement
 * that is a part of a trigger-program. 
 *
 * Instances of struct TriggerStep are stored in a singly linked list (linked
 * using the "pNext" member) referenced by the "step_list" member of the 
 * associated struct Trigger instance. The first element of the linked list is

#ifndef SQLITE_OMIT_TRIGGER
  void sqlite3BeginTrigger(Parse*, Token*,Token*,int,int,IdList*,SrcList*,
                           int,Expr*,int);
  void sqlite3FinishTrigger(Parse*, TriggerStep*, Token*);
  void sqlite3DropTrigger(Parse*, SrcList*);
  void sqlite3DropTriggerPtr(Parse*, Trigger*, int);
  int sqlite3TriggersExist(Parse* , Trigger* , int , int , int, ExprList*);
  int sqlite3CodeRowTrigger(Parse*, int, ExprList*, int, Table *, int, int, 
                           int, int);
  void sqliteViewTriggers(Parse*, Table*, Expr*, int, ExprList*);
  void sqlite3DeleteTriggerStep(TriggerStep*);
  TriggerStep *sqlite3TriggerSelectStep(Select*);
  TriggerStep *sqlite3TriggerInsertStep(Token*, IdList*, ExprList*,Select*,int);
  TriggerStep *sqlite3TriggerUpdateStep(Token*, ExprList*, Expr*, int);

  }
  if( sqlite3HashFind(&(db->aDb[iDb].trigHash), zName,pName->n+1) ){
    sqlite3ErrorMsg(pParse, "trigger %T already exists", pName);
    goto trigger_cleanup;
  }

  /* Do not create a trigger on a system table */
  if( (iDb!=1 && sqlite3StrICmp(pTab->zName, MASTER_NAME)==0) || 
      (iDb==1 && sqlite3StrICmp(pTab->zName, TEMP_MASTER_NAME)==0) 
  ){
    sqlite3ErrorMsg(pParse, "cannot create trigger on system table");
    pParse->nErr++;
    goto trigger_cleanup;
  }

  /* INSTEAD of triggers are only for views and views only support INSTEAD
  ** of triggers.

  pTrigger->name = zName;
  zName = 0;
  pTrigger->table = sqliteStrDup(pTableName->a[0].zName);
  if( sqlite3_malloc_failed ) goto trigger_cleanup;
  pTrigger->iDb = iDb;
  pTrigger->iTabDb = pTab->iDb;
  pTrigger->op = op;
  pTrigger->tr_tm = tr_tm;
  pTrigger->pWhen = sqlite3ExprDup(pWhen);
  pTrigger->pColumns = sqlite3IdListDup(pColumns);
  pTrigger->foreach = foreach;
  sqlite3TokenCopy(&pTrigger->nameToken,pName);
  assert( pParse->pNewTrigger==0 );
  pParse->pNewTrigger = pTrigger;

  for(e=0; e<pEList->nExpr; e++){
    if( sqlite3IdListIndex(pIdList, pEList->a[e].zName)>=0 ) return 1;
  }
  return 0; 
}

/*
 * Returns true if a trigger matching op, tr_tm and foreach that is NOT already
 * on the Parse objects trigger-stack (to prevent recursive trigger firing) is
 * found in the list specified as pTrigger.




 */
int sqlite3TriggersExist(
  Parse *pParse,          /* Used to check for recursive triggers */
  Trigger *pTrigger,      /* A list of triggers associated with a table */
  int op,                 /* one of TK_DELETE, TK_INSERT, TK_UPDATE */
  int tr_tm,              /* one of TK_BEFORE, TK_AFTER */
  int foreach,            /* one of TK_ROW or TK_STATEMENT */
  ExprList *pChanges      /* Columns that change in an UPDATE statement */
){
  Trigger * pTriggerCursor;


  pTriggerCursor = pTrigger;
  while( pTriggerCursor ){
    if( pTriggerCursor->op == op && 
	pTriggerCursor->tr_tm == tr_tm && 
	pTriggerCursor->foreach == foreach &&
	checkColumnOverLap(pTriggerCursor->pColumns, pChanges) ){
      TriggerStack * ss;
      ss = pParse->trigStack;
      while( ss && ss->pTrigger != pTrigger ){
	ss = ss->pNext;
      }
      if( !ss )return 1;

    }
    pTriggerCursor = pTriggerCursor->pNext;
  }


  return 0;
}

/*
** Convert the pStep->target token into a SrcList and return a pointer
** to that SrcList.
**
** This routine adds a specific database name, if needed, to the target when

**    trigger program(s).
**
*/
int sqlite3CodeRowTrigger(
  Parse *pParse,       /* Parse context */
  int op,              /* One of TK_UPDATE, TK_INSERT, TK_DELETE */
  ExprList *pChanges,  /* Changes list for any UPDATE OF triggers */
  int tr_tm,           /* One of TK_BEFORE, TK_AFTER */
  Table *pTab,         /* The table to code triggers from */
  int newIdx,          /* The indice of the "new" row to access */
  int oldIdx,          /* The indice of the "old" row to access */
  int orconf,          /* ON CONFLICT policy */
  int ignoreJump       /* Instruction to jump to for RAISE(IGNORE) */
){
  Trigger *pTrigger;
  TriggerStack *pStack;
  TriggerStack trigStackEntry;

  assert(op == TK_UPDATE || op == TK_INSERT || op == TK_DELETE);
  assert(tr_tm == TK_BEFORE || tr_tm == TK_AFTER );

  assert(newIdx != -1 || oldIdx != -1);

  pTrigger = pTab->pTrigger;
  while( pTrigger ){
    int fire_this = 0;

    /* determine whether we should code this trigger */
    if( pTrigger->op == op && pTrigger->tr_tm == tr_tm && 
        pTrigger->foreach == TK_ROW ){
      fire_this = 1;
      for(pStack=pParse->trigStack; pStack; pStack=pStack->pNext){
        if( pStack->pTrigger==pTrigger ){
	  fire_this = 0;
	}
      }
      if( op == TK_UPDATE && pTrigger->pColumns &&

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle UPDATE statements.
**
** $Id: update.c,v 1.97 2004/11/23 01:47:30 drh Exp $
*/
#include "sqliteInt.h"

/*
** Process an UPDATE statement.
**
**   UPDATE OR IGNORE table_wxyz SET a=b, c=d WHERE e<5 AND f NOT NULL;

  int chngRecno;         /* True if the record number is being changed */
  Expr *pRecnoExpr = 0;  /* Expression defining the new record number */
  int openAll = 0;       /* True if all indices need to be opened */
  AuthContext sContext;  /* The authorization context */

#ifndef SQLITE_OMIT_TRIGGER
  int isView;                  /* Trying to update a view */
  int before_triggers;         /* True if there are any BEFORE triggers */
  int after_triggers;          /* True if there are any AFTER triggers */
  int row_triggers_exist = 0;  /* True if any row triggers exist */
#endif

  int newIdx      = -1;  /* index of trigger "new" temp table       */
  int oldIdx      = -1;  /* index of trigger "old" temp table       */

  sContext.pParse = 0;
  if( pParse->nErr || sqlite3_malloc_failed ) goto update_cleanup;
  db = pParse->db;
  assert( pTabList->nSrc==1 );

  /* Locate the table which we want to update. 
  */
  pTab = sqlite3SrcListLookup(pParse, pTabList);
  if( pTab==0 ) goto update_cleanup;

  /* Figure out if we have any triggers and if the table being
  ** updated is a view
  */
#ifndef SQLITE_OMIT_TRIGGER
  before_triggers = sqlite3TriggersExist(pParse, pTab->pTrigger, 
                         TK_UPDATE, TK_BEFORE, TK_ROW, pChanges);
  after_triggers = sqlite3TriggersExist(pParse, pTab->pTrigger, 
                         TK_UPDATE, TK_AFTER, TK_ROW, pChanges);
  row_triggers_exist = before_triggers || after_triggers;
  isView = pTab->pSelect!=0;
#else
# define before_triggers 0
# define after_triggers 0
# define row_triggers_exist 0
# define isView 0
#endif
#ifdef SQLITE_OMIT_VIEW
# undef isView
# define isView 0
#endif

  if( sqlite3IsReadOnly(pParse, pTab, before_triggers) ){
    goto update_cleanup;
  }
  if( isView ){
    if( sqlite3ViewGetColumnNames(pParse, pTab) ){
      goto update_cleanup;
    }
  }
  aXRef = sqliteMallocRaw( sizeof(int) * pTab->nCol );
  if( aXRef==0 ) goto update_cleanup;
  for(i=0; i<pTab->nCol; i++) aXRef[i] = -1;

  /* If there are FOR EACH ROW triggers, allocate cursors for the
  ** special OLD and NEW tables
  */
  if( row_triggers_exist ){
    newIdx = pParse->nTab++;
    oldIdx = pParse->nTab++;
  }

  /* Allocate a cursors for the main database table and for all indices.
  ** The index cursors might not be used, but if they are used they
  ** need to occur right after the database cursor.  So go ahead and

  /* Initialize the count of updated rows
  */
  if( db->flags & SQLITE_CountRows && !pParse->trigStack ){
    sqlite3VdbeAddOp(v, OP_Integer, 0, 0);
  }

  if( row_triggers_exist ){
    /* Create pseudo-tables for NEW and OLD
    */
    sqlite3VdbeAddOp(v, OP_OpenPseudo, oldIdx, 0);
    sqlite3VdbeAddOp(v, OP_SetNumColumns, oldIdx, pTab->nCol);
    sqlite3VdbeAddOp(v, OP_OpenPseudo, newIdx, 0);
    sqlite3VdbeAddOp(v, OP_SetNumColumns, newIdx, pTab->nCol);

    sqlite3VdbeAddOp(v, OP_PutIntKey, newIdx, 0);
    if( !isView ){
      sqlite3VdbeAddOp(v, OP_Close, iCur, 0);
    }

    /* Fire the BEFORE and INSTEAD OF triggers
    */
    if( sqlite3CodeRowTrigger(pParse, TK_UPDATE, pChanges, TK_BEFORE, pTab, 
          newIdx, oldIdx, onError, addr) ){
      goto update_cleanup;
    }
  }

  if( !isView ){
    /* 

    /* Loop over every record that needs updating.  We have to load
    ** the old data for each record to be updated because some columns
    ** might not change and we will need to copy the old value.
    ** Also, the old data is needed to delete the old index entires.
    ** So make the cursor point at the old record.
    */
    if( !row_triggers_exist ){
      sqlite3VdbeAddOp(v, OP_ListRewind, 0, 0);
      addr = sqlite3VdbeAddOp(v, OP_ListRead, 0, 0);
      sqlite3VdbeAddOp(v, OP_Dup, 0, 0);
    }
    sqlite3VdbeAddOp(v, OP_NotExists, iCur, addr);

    /* If the record number will change, push the record number as it

  if( db->flags & SQLITE_CountRows && !pParse->trigStack){
    sqlite3VdbeAddOp(v, OP_AddImm, 1, 0);
  }

  /* If there are triggers, close all the cursors after each iteration
  ** through the loop.  The fire the after triggers.
  */
  if( row_triggers_exist ){
    if( !isView ){
      for(i=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){
        if( openAll || aIdxUsed[i] )
          sqlite3VdbeAddOp(v, OP_Close, iCur+i+1, 0);
      }
      sqlite3VdbeAddOp(v, OP_Close, iCur, 0);
    }
    if( sqlite3CodeRowTrigger(pParse, TK_UPDATE, pChanges, TK_AFTER, pTab, 
          newIdx, oldIdx, onError, addr) ){
      goto update_cleanup;
    }
  }

  /* Repeat the above with the next record to be updated, until
  ** all record selected by the WHERE clause have been updated.
  */
  sqlite3VdbeAddOp(v, OP_Goto, 0, addr);
  sqlite3VdbeChangeP2(v, addr, sqlite3VdbeCurrentAddr(v));
  sqlite3VdbeAddOp(v, OP_ListReset, 0, 0);

  /* Close all tables if there were no FOR EACH ROW triggers */
  if( !row_triggers_exist ){
    for(i=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){
      if( openAll || aIdxUsed[i] ){
        sqlite3VdbeAddOp(v, OP_Close, iCur+i+1, 0);
      }
    }
    sqlite3VdbeAddOp(v, OP_Close, iCur, 0);
  }else{

**
** Various scripts scan this source file in order to generate HTML
** documentation, headers files, or other derived files.  The formatting
** of the code in this file is, therefore, important.  See other comments
** in this file for details.  If in doubt, do not deviate from existing
** commenting and indentation practices when changing or adding code.
**
** $Id: vdbe.c,v 1.432 2004/12/07 12:29:18 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>
#include "vdbeInt.h"

/*