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 SELECT statements in SQLite.
**
** $Id: select.c,v 1.308 2006/03/17 00:04:03 drh Exp $
*/
#include "sqliteInt.h"


/*
** Delete all the content of a Select structure but do not deallocate
** the select structure itself.

/*
** If the inner loop was generated using a non-null pOrderBy argument,
** then the results were placed in a sorter.  After the loop is terminated
** we need to run the sorter and output the results.  The following
** routine generates the code needed to do that.
*/
static void generateSortTail(
  Parse *pParse,   /* Parsing context */
  Select *p,       /* The SELECT statement */
  Vdbe *v,         /* Generate code into this VDBE */
  int nColumn,     /* Number of columns of data */
  int eDest,       /* Write the sorted results here */
  int iParm        /* Optional parameter associated with eDest */
){
  int brk = sqlite3VdbeMakeLabel(v);
  int cont = sqlite3VdbeMakeLabel(v);
  int addr;
  int iTab;
  int pseudoTab;
  ExprList *pOrderBy = p->pOrderBy;

  iTab = pOrderBy->iECursor;
  if( eDest==SRT_Callback || eDest==SRT_Subroutine ){
    pseudoTab = pParse->nTab++;
    sqlite3VdbeAddOp(v, OP_OpenPseudo, pseudoTab, 0);
    sqlite3VdbeAddOp(v, OP_SetNumColumns, pseudoTab, nColumn);
  }
  addr = 1 + sqlite3VdbeAddOp(v, OP_Sort, iTab, brk);
  codeOffset(v, p, cont, 0);
  if( eDest==SRT_Callback || eDest==SRT_Subroutine ){
    sqlite3VdbeAddOp(v, OP_Integer, 1, 0);
  }
  sqlite3VdbeAddOp(v, OP_Column, iTab, pOrderBy->nExpr + 1);
  switch( eDest ){
    case SRT_Table:
    case SRT_VirtualTab: {
      sqlite3VdbeAddOp(v, OP_NewRowid, iParm, 0);
      sqlite3VdbeAddOp(v, OP_Pull, 1, 0);
      sqlite3VdbeAddOp(v, OP_Insert, iParm, 0);

      /* The LIMIT clause will terminate the loop for us */
      break;
    }
#endif
    case SRT_Callback:
    case SRT_Subroutine: {
      int i;

      sqlite3VdbeAddOp(v, OP_Insert, pseudoTab, 0);
      for(i=0; i<nColumn; i++){
        sqlite3VdbeAddOp(v, OP_Column, pseudoTab, i);
      }
      if( eDest==SRT_Callback ){
        sqlite3VdbeAddOp(v, OP_Callback, nColumn, 0);
      }else{
        sqlite3VdbeAddOp(v, OP_Gosub, 0, iParm);
      }

      break;
    }
    default: {
      /* Do nothing */
      break;
    }
  }

  /* Jump to the end of the loop when the LIMIT is reached
  */
  if( p->iLimit>=0 ){
    sqlite3VdbeAddOp(v, OP_MemIncr, -1, p->iLimit);
    sqlite3VdbeAddOp(v, OP_IfMemZero, p->iLimit, brk);
  }

  /* The bottom of the loop
  */
  sqlite3VdbeResolveLabel(v, cont);
  sqlite3VdbeAddOp(v, OP_Next, iTab, addr);
  sqlite3VdbeResolveLabel(v, brk);
  if( eDest==SRT_Callback || eDest==SRT_Subroutine ){
    sqlite3VdbeAddOp(v, OP_Close, pseudoTab, 0);
  }

}

/*
** Return a pointer to a string containing the 'declaration type' of the
** expression pExpr. The string may be treated as static by the caller.
**
** The declaration type is the exact datatype definition extracted from the

      assert( p->pRightmost==p );
      assert( p->addrOpenVirt[2]>=0 );
      addr = p->addrOpenVirt[2];
      sqlite3VdbeChangeP2(v, addr, p->pEList->nExpr+2);
      pKeyInfo->nField = nOrderByExpr;
      sqlite3VdbeChangeP3(v, addr, (char*)pKeyInfo, P3_KEYINFO_HANDOFF);
      pKeyInfo = 0;
      generateSortTail(pParse, p, v, p->pEList->nExpr, eDest, iParm);
    }

    sqliteFree(pKeyInfo);
  }

multi_select_end:
  return rc;

    
  } /* endif aggregate query */

  /* If there is an ORDER BY clause, then we need to sort the results
  ** and send them to the callback one by one.
  */
  if( pOrderBy ){
    generateSortTail(pParse, p, v, pEList->nExpr, eDest, iParm);
  }

#ifndef SQLITE_OMIT_SUBQUERY
  /* If this was a subquery, we have now converted the subquery into a
  ** temporary table.  So set the SrcList_item.isPopulated flag to prevent
  ** this subquery from being evaluated again and to force the use of
  ** the temporary table.

/*
** 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 1.490 2006/03/17 00:04:04 drh Exp $
*/
#ifndef _SQLITEINT_H_
#define _SQLITEINT_H_

/*
** Extra interface definitions for those who need them
*/

  TriggerStep *sqlite3TriggerUpdateStep(Token*, ExprList*, Expr*, int);
  TriggerStep *sqlite3TriggerDeleteStep(Token*, Expr*);
  void sqlite3DeleteTrigger(Trigger*);
  void sqlite3UnlinkAndDeleteTrigger(sqlite3*,int,const char*);
#else
# define sqlite3TriggersExist(A,B,C,D,E,F) 0
# define sqlite3DeleteTrigger(A)
# define sqlite3DropTriggerPtr(A,B)
# define sqlite3UnlinkAndDeleteTrigger(A,B,C)
# define sqlite3CodeRowTrigger(A,B,C,D,E,F,G,H,I) 0
#endif

int sqlite3JoinType(Parse*, Token*, Token*, Token*);
void sqlite3CreateForeignKey(Parse*, ExprList*, Token*, ExprList*, int);
void sqlite3DeferForeignKey(Parse*, int);

**
** 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 1.546 2006/03/17 00:04:04 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>
#include "vdbeInt.h"

/*

  **
  ** We also compute the number of columns in the record.  For cursors,
  ** the number of columns is stored in the Cursor.nField element.  For
  ** records on the stack, the next entry down on the stack is an integer
  ** which is the number of records.
  */
  assert( p1<0 || p->apCsr[p1]!=0 );
#if 0
  if( p1<0 ){
    /* Take the record off of the stack */
    Mem *pRec = &pTos[p1];
    Mem *pCnt = &pRec[-1];
    assert( pRec>=p->aStack );
    assert( pRec->flags & MEM_Blob );
    payloadSize = pRec->n;
    zRec = pRec->z;
    assert( pCnt>=p->aStack );
    assert( pCnt->flags & MEM_Int );
    nField = pCnt->i;
    pCrsr = 0;
  }else
#endif
  if( (pC = p->apCsr[p1])->pCursor!=0 ){
    /* The record is stored in a B-Tree */
    rc = sqlite3VdbeCursorMoveto(pC);
    if( rc ) goto abort_due_to_error;
    zRec = 0;
    pCrsr = pC->pCursor;
    if( pC->nullRow ){
      payloadSize = 0;
    }else if( pC->cacheStatus==p->cacheCtr ){
      payloadSize = pC->payloadSize;
      zRec = (char*)pC->aRow;
    }else if( pC->isIndex ){
      i64 payloadSize64;
      sqlite3BtreeKeySize(pCrsr, &payloadSize64);
      payloadSize = payloadSize64;
    }else{
      sqlite3BtreeDataSize(pCrsr, &payloadSize);
    }
    nField = pC->nField;

  }else if( pC->pseudoTable ){
    /* The record is the sole entry of a pseudo-table */
    payloadSize = pC->nData;
    zRec = pC->pData;
    pC->cacheStatus = CACHE_STALE;
    assert( payloadSize==0 || zRec!=0 );
    nField = pC->nField;
    pCrsr = 0;

  }else{
    zRec = 0;
    payloadSize = 0;
    pCrsr = 0;
    nField = 0;
  }

    }else{
      pTos->flags = MEM_Null;
    }
  }

  /* If we dynamically allocated space to hold the data (in the
  ** sqlite3VdbeMemFromBtree() call above) then transfer control of that
  ** dynamically allocated space over to the pTos structure.
  ** This prevents a memory copy.
  */
  if( (sMem.flags & MEM_Dyn)!=0 ){
    assert( pTos->flags & MEM_Ephem );
    assert( pTos->flags & (MEM_Str|MEM_Blob) );
    assert( pTos->z==sMem.z );
    assert( sMem.flags & MEM_Term );

    }
  }
  pCx->nField = pOp->p2;
  pCx->isIndex = !pCx->isTable;
  break;
}


/* Opcode: OpenPseudo P1 * *
**
** Open a new cursor that points to a fake table that contains a single
** row of data.  Any attempt to write a second row of data causes the
** first row to be deleted.  All data is deleted when the cursor is
** closed.
**
** A pseudo-table created by this opcode is useful for holding the
** NEW or OLD tables in a trigger.  Also used to hold the a single
** row output from the sorter so that the row can be decomposed into
** individual columns using the OP_Column opcode.
*/
case OP_OpenPseudo: {       /* no-push */
  int i = pOp->p1;
  Cursor *pCx;
  assert( i>=0 );
  pCx = allocateCursor(p, i, -1);
  if( pCx==0 ) goto no_mem;
  pCx->nullRow = 1;
  pCx->pseudoTable = 1;
  pCx->pIncrKey = &pCx->bogusIncrKey;
  pCx->isTable = 1;
  pCx->isIndex = 0;
  break;
}


/* Opcode: Close P1 * *
**
** Close a cursor previously opened as P1.  If P1 is not
** currently open, this instruction is a no-op.
*/
case OP_Close: {       /* no-push */

    }
    if( pTos->flags & MEM_Null ){
      pTos->z = 0;
      pTos->n = 0;
    }else{
      assert( pTos->flags & (MEM_Blob|MEM_Str) );
    }

    if( pC->pseudoTable ){
      sqliteFree(pC->pData);
      pC->iKey = iKey;
      pC->nData = pTos->n;
      if( pTos->flags & MEM_Dyn ){
        pC->pData = pTos->z;
        pTos->flags = MEM_Null;
      }else{
        pC->pData = sqliteMallocRaw( pC->nData+2 );
        if( !pC->pData ) goto no_mem;
        memcpy(pC->pData, pTos->z, pC->nData);
        pC->pData[pC->nData] = 0;
        pC->pData[pC->nData+1] = 0;
      }
      pC->nullRow = 0;
    }else{

      rc = sqlite3BtreeInsert(pC->pCursor, 0, iKey, pTos->z, pTos->n);

    }

    
    pC->rowidIsValid = 0;
    pC->deferredMoveto = 0;
    pC->cacheStatus = CACHE_STALE;

    /* Invoke the update-hook if required. */
    if( rc==SQLITE_OK && db->xUpdateCallback && pOp->p3 ){

      pTos->z = z;
    }
    if( pC->isIndex ){
      sqlite3BtreeKey(pCrsr, 0, n, pTos->z);
    }else{
      sqlite3BtreeData(pCrsr, 0, n, pTos->z);
    }

  }else if( pC->pseudoTable ){
    pTos->n = pC->nData;
    pTos->z = pC->pData;
    pTos->flags = MEM_Blob|MEM_Ephem;

  }else{
    pTos->flags = MEM_Null;
  }
  pTos->enc = SQLITE_UTF8;  /* In case the blob is ever cast to text */
  break;
}