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 UPDATE statements.
**
** $Id: update.c,v 1.142 2007/12/12 12:00:46 drh Exp $
*/
#include "sqliteInt.h"

#ifndef SQLITE_OMIT_VIRTUALTABLE
/* Forward declaration */
static void updateVirtualTable(
  Parse *pParse,       /* The parsing context */

    sqlite3VdbeAddOp(v, OP_SetNumColumns, oldIdx, pTab->nCol);
    sqlite3VdbeAddOp(v, OP_OpenPseudo, newIdx, 0);
    sqlite3VdbeAddOp(v, OP_SetNumColumns, newIdx, pTab->nCol);

    /* The top of the update loop for when there are triggers.
    */
    addr = sqlite3VdbeAddOp(v, OP_FifoRead, 0, 0);
    sqlite3VdbeAddOp(v, OP_StackDepth, -1, 0);
    mem1 = pParse->nMem++;
    sqlite3VdbeAddOp(v, OP_MemStore, mem1, 0);
    
    if( !isView ){
      /* Open a cursor and make it point to the record that is
      ** being updated.
      */

    ** 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 entries.
    ** So make the cursor point at the old record.
    */
    if( !triggers_exist ){
      addr = sqlite3VdbeAddOp(v, OP_FifoRead, 0, 0);
      sqlite3VdbeAddOp(v, OP_StackDepth, -1, 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
    ** will be after the update. (The old record number is currently
    ** on top of the stack.)

**
** 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 1.657 2007/12/12 12:00:46 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>
#include "vdbeInt.h"

/*
** The following global variable is incremented every time a cursor

  if( rc==SQLITE_BUSY ){
    p->rc = rc = SQLITE_BUSY;
  }else{
    rc = p->rc ? SQLITE_ERROR : SQLITE_DONE;
  }
  goto vdbe_return;
}

/* Opcode:  StackDepth P1 * *
**
** If P1 is less than zero, then store the current stack depth
** in P1.  If P1 is zero or greater, verify that the current stack
** depth is equal to P1 and throw an exception if it is not.
**
** This opcode is used for internal consistency checking.
*/
case OP_StackDepth: {       /* no-push */
  if( pOp->p1<0 ){
    pOp->p1 = pTos - p->aStack + 1;
  }else if( pOp->p1!=pTos - p->aStack + 1 ){
    p->pTos = pTos;
    p->rc = SQLITE_ERROR;
    p->pc = pc;
    p->errorAction = OE_Rollback;
    sqlite3SetString(&p->zErrMsg, "internal VDBE stack overflow", (char*)0);
    goto vdbe_return;
  }
  break;
}

/* Opcode: Integer P1 * *
**
** The 32-bit integer value P1 is pushed onto the stack.
*/
case OP_Integer: {
  pTos++;