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
** in order to generate code for DELETE FROM statements.
**
** $Id: delete.c,v 1.145 2008/01/04 13:24:29 danielk1977 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.

  if( v==0 ){
    goto delete_from_cleanup;
  }
  if( pParse->nested==0 ) sqlite3VdbeCountChanges(v);
  sqlite3BeginWriteOperation(pParse, triggers_exist, iDb);

  if( triggers_exist ){

    int iGoto = sqlite3VdbeAddOp0(v, OP_Goto);
    addr = sqlite3VdbeMakeLabel(v);

    iBeginBeforeTrigger = sqlite3VdbeCurrentAddr(v);
    (void)sqlite3CodeRowTrigger(pParse, TK_DELETE, 0, TRIGGER_BEFORE, pTab,
        -1, oldIdx, (pParse->trigStack)?pParse->trigStack->orconf:OE_Default,
        addr, &old_col_mask, 0);
    iEndBeforeTrigger = sqlite3VdbeAddOp0(v, OP_Goto);

    iBeginAfterTrigger = sqlite3VdbeCurrentAddr(v);
    (void)sqlite3CodeRowTrigger(pParse, TK_DELETE, 0, TRIGGER_AFTER, pTab, -1,
        oldIdx, (pParse->trigStack)?pParse->trigStack->orconf:OE_Default,
        addr, &old_col_mask, 0);
    iEndAfterTrigger = sqlite3VdbeAddOp0(v, OP_Goto);

    sqlite3VdbeJumpHere(v, iGoto);
  }

  /* If we are trying to delete from a view, realize that view into
  ** a ephemeral table.
  */
  if( isView ){

      }
    }
  } 
  /* The usual case: There is a WHERE clause so we have to scan through
  ** the table and pick which records to delete.
  */
  else{
    int iRowid = ++pParse->nMem;    /* Used for storing value read from fifo */

    /* Begin the database scan
    */
    pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, 0);
    if( pWInfo==0 ) goto delete_from_cleanup;

    /* Remember the rowid of every item to be deleted.
    */
    sqlite3VdbeAddOp1(v, IsVirtual(pTab) ? OP_VRowid : OP_Rowid, iCur);
    sqlite3VdbeAddOp0(v, OP_FifoWrite);
    if( db->flags & SQLITE_CountRows ){
      sqlite3VdbeAddOp2(v, OP_MemIncr, 1, memCnt);
    }

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

**    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 1.155 2008/01/03 23:44:53 drh Exp $
*/
#include "sqliteInt.h"

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

  Expr *pRowidExpr = 0;  /* Expression defining the new record number */
  int openAll = 0;       /* True if all indices need to be opened */
  AuthContext sContext;  /* The authorization context */
  NameContext sNC;       /* The name-context to resolve expressions in */
  int iDb;               /* Database containing the table being updated */
  int memCnt = 0;        /* Memory cell used for counting rows changed */
  int mem1;      /* Memory address storing the rowid for next row to update */


#ifndef SQLITE_OMIT_TRIGGER
  int isView;                  /* Trying to update a view */
  int triggers_exist = 0;      /* True if any row triggers exist */
#endif
  int iBeginAfterTrigger;      /* Address of after trigger program */
  int iEndAfterTrigger;        /* Exit of after trigger program */

  /* Begin the database scan
  */
  pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, 0);
  if( pWInfo==0 ) goto update_cleanup;

  /* Remember the rowid of every item to be updated.
  */

  sqlite3VdbeAddOp2(v, IsVirtual(pTab) ? OP_VRowid : OP_Rowid, iCur, 0);
  sqlite3VdbeAddOp2(v, OP_FifoWrite, 0, 0);

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

  /* Initialize the count of updated rows
  */

      if( openAll || aIdxUsed[i] ){
        KeyInfo *pKey = sqlite3IndexKeyinfo(pParse, pIdx);
        sqlite3VdbeAddOp4(v, OP_OpenWrite, iCur+i+1, pIdx->tnum, iDb,
                       (char*)pKey, P4_KEYINFO_HANDOFF);
        assert( pParse->nTab>iCur+i+1 );
      }
    }

  }
  
  /* Jump back to this point if a trigger encounters an IGNORE constraint. */
  if( triggers_exist ){
    sqlite3VdbeResolveLabel(v, addr);
  }

  /* Top of the update loop */
  addr = sqlite3VdbeAddOp2(v, OP_FifoRead, 0, 0);
  sqlite3VdbeAddOp2(v, OP_StackDepth, -1, 0);
  sqlite3VdbeAddOp2(v, OP_MemStore, mem1, 0);

  if( triggers_exist ){
    /* Make cursor iCur point to the record that is being updated.
    */
    sqlite3VdbeAddOp2(v, OP_NotExists, iCur, addr);

    /* Generate the OLD table
    */
    sqlite3VdbeAddOp2(v, OP_Rowid, iCur, 0);
    if( !old_col_mask ){
      sqlite3VdbeAddOp2(v, OP_Null, 0, 0);
    }else{

      sqlite3TableAffinityStr(v, pTab);
    }
    if( pParse->nErr ) goto update_cleanup;
    sqlite3CodeInsert(pParse, newIdx, 0);

    sqlite3VdbeAddOp2(v, OP_Goto, 0, iBeginBeforeTrigger);
    sqlite3VdbeJumpHere(v, iEndBeforeTrigger);

    if( !isView ){
      sqlite3VdbeAddOp2(v, OP_MemLoad, mem1, 0);
    }
  }

  if( !isView && !IsVirtual(pTab) ){

    /* 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 entries.
    ** So make the cursor point at the old record.
    */
    sqlite3VdbeAddOp2(v, OP_NotExists, iCur, addr);
    sqlite3VdbeAddOp2(v, OP_MemLoad, mem1, 0);

    /* 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.)
    */
    if( chngRowid ){
      sqlite3ExprCode(pParse, pRowidExpr, 0);

**
** 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 1.675 2008/01/04 13:24:29 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>
#include "vdbeInt.h"

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

  pTos->enc = SQLITE_UTF8;
  sqlite3VdbeChangeEncoding(pTos, encoding);
  sqlite3_free(aRoot);
  break;
}
#endif /* SQLITE_OMIT_INTEGRITY_CHECK */

/* Opcode: FifoWrite * * *
**
** Write the integer on the top of the stack into the Fifo.
*/
case OP_FifoWrite: {        /* no-push */

  assert( pTos>=p->aStack );
  sqlite3VdbeMemIntegerify(pTos);
  if( sqlite3VdbeFifoPush(&p->sFifo, pTos->u.i)==SQLITE_NOMEM ){
    goto no_mem;
  }
  assert( (pTos->flags & MEM_Dyn)==0 );
  pTos--;
  break;
}

/* Opcode: FifoRead P1 P2 *
**
** Attempt to read a single integer from the Fifo. If P1 is zero,
** push the result onto the stack. Otherwise, store the read integer 
** in register P1.
** 
** If the Fifo is empty do not push an entry onto the stack or set
** a memory register but instead jump to P2.
*/
case OP_FifoRead: {
  i64 v;
  CHECK_FOR_INTERRUPT;
  if( sqlite3VdbeFifoPop(&p->sFifo, &v)==SQLITE_DONE ){
    pc = pOp->p2 - 1;
  }else{
    Mem *pOut;
    if( pOp->p1 ){
      pOut = &p->aMem[pOp->p1];
    }else{
      pOut = ++pTos;
    }
    sqlite3VdbeMemSetInt64(pOut, v);
  }
  break;
}

#ifndef SQLITE_OMIT_TRIGGER
/* Opcode: ContextPush * * *