**    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 1.92 2002/06/06 23:42:28 drh Exp $
*/
#include "sqliteInt.h"

/*
** Allocate a new Select structure and return a pointer to that
** structure.
*/
................................................................................
**
** The pEList is used to determine the values for each column in the
** result row.  Except  if pEList==NULL, then we just read nColumn
** elements from the srcTab table.
*/
static int selectInnerLoop(
  Parse *pParse,          /* The parser context */

  ExprList *pEList,       /* List of values being extracted */
  int srcTab,             /* Pull data from this table */
  int nColumn,            /* Number of columns in the source table */
  ExprList *pOrderBy,     /* If not NULL, sort results using this key */
  int distinct,           /* If >=0, make sure results are distinct */
  int eDest,              /* How to dispose of the results */
  int iParm,              /* An argument to the disposal method */
  int iContinue,          /* Jump here to continue with next row */
  int iBreak              /* Jump here to break out of the inner loop */
){
  Vdbe *v = pParse->pVdbe;
  int i;
  if( v==0 ) return 0;













  /* Pull the requested columns.
  */
  if( pEList ){
    for(i=0; i<pEList->nExpr; i++){
      sqliteExprCode(pParse, pEList->a[i].pExpr);
    }
................................................................................
  if( eDest==SRT_Discard ){
    sqliteVdbeAddOp(v, OP_Pop, nColumn, 0);
  }else

  /* If none of the above, send the data to the callback function.
  */
  {

    sqliteVdbeAddOp(v, OP_Callback, nColumn, iBreak);
  }
  return 0;
}

/*
** 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(Vdbe *v, int nColumn){
  int end = sqliteVdbeMakeLabel(v);
  int addr;
  sqliteVdbeAddOp(v, OP_Sort, 0, 0);
  addr = sqliteVdbeAddOp(v, OP_SortNext, 0, end);






  sqliteVdbeAddOp(v, OP_SortCallback, nColumn, end);
  sqliteVdbeAddOp(v, OP_Goto, 0, addr);
  sqliteVdbeResolveLabel(v, end);
  sqliteVdbeAddOp(v, OP_SortReset, 0, 0);
}

/*
** Generate code that will tell the VDBE how many columns there
................................................................................
        if( eDest==SRT_Callback ){
          generateColumnNames(pParse, p->base, 0, p->pEList);
        }
        iBreak = sqliteVdbeMakeLabel(v);
        iCont = sqliteVdbeMakeLabel(v);
        sqliteVdbeAddOp(v, OP_Rewind, unionTab, iBreak);
        iStart = sqliteVdbeCurrentAddr(v);
        rc = selectInnerLoop(pParse, 0, unionTab, p->pEList->nExpr,
                             p->pOrderBy, -1, eDest, iParm, 
                             iCont, iBreak);
        if( rc ) return 1;
        sqliteVdbeResolveLabel(v, iCont);
        sqliteVdbeAddOp(v, OP_Next, unionTab, iStart);
        sqliteVdbeResolveLabel(v, iBreak);
        sqliteVdbeAddOp(v, OP_Close, unionTab, 0);
        if( p->pOrderBy ){
          generateSortTail(v, p->pEList->nExpr);
        }
      }
      break;
    }
    case TK_INTERSECT: {
      int tab1, tab2;
      int iCont, iBreak, iStart;
................................................................................
        generateColumnNames(pParse, p->base, 0, p->pEList);
      }
      iBreak = sqliteVdbeMakeLabel(v);
      iCont = sqliteVdbeMakeLabel(v);
      sqliteVdbeAddOp(v, OP_Rewind, tab1, iBreak);
      iStart = sqliteVdbeAddOp(v, OP_FullKey, tab1, 0);
      sqliteVdbeAddOp(v, OP_NotFound, tab2, iCont);
      rc = selectInnerLoop(pParse, 0, tab1, p->pEList->nExpr,
                             p->pOrderBy, -1, eDest, iParm, 
                             iCont, iBreak);
      if( rc ) return 1;
      sqliteVdbeResolveLabel(v, iCont);
      sqliteVdbeAddOp(v, OP_Next, tab1, iStart);
      sqliteVdbeResolveLabel(v, iBreak);
      sqliteVdbeAddOp(v, OP_Close, tab2, 0);
      sqliteVdbeAddOp(v, OP_Close, tab1, 0);
      if( p->pOrderBy ){
        generateSortTail(v, p->pEList->nExpr);
      }
      break;
    }
  }
  assert( p->pEList && pPrior->pEList );
  if( p->pEList->nExpr!=pPrior->pEList->nExpr ){
    sqliteSetString(&pParse->zErrMsg, "SELECTs to the left and right of ",
................................................................................
**   (5)  The subquery is not DISTINCT or the outer query does not use
**        aggregates.
**
**   (6)  The subquery does not use aggregates or the outer query is not
**        DISTINCT.
**
**   (7)  The subquery has a FROM clause.








**
** In this routine, the "p" parameter is a pointer to the outer query.
** The subquery is p->pSrc->a[iFrom].  isAgg is true if the outer query
** uses aggregates and subqueryIsAgg is true if the subquery uses aggregates.
**
** If flattening is not attempted, this routine is a no-op and return 0.
** If flattening is attempted this routine returns 1.
................................................................................
  pSub = pSrc->a[iFrom].pSelect;
  assert( pSub!=0 );
  if( isAgg && subqueryIsAgg ) return 0;
  if( subqueryIsAgg && pSrc->nSrc>1 ) return 0;
  pSubSrc = pSub->pSrc;
  assert( pSubSrc );
  if( pSubSrc->nSrc!=1 ) return 0;
  if( pSub->isDistinct && pSrc->nSrc>1 ) return 0;
  if( pSub->isDistinct && isAgg ) return 0;

  if( p->isDistinct && subqueryIsAgg ) return 0;

  /* If we reach this point, it means flattening is permitted for the
  ** i-th entry of the FROM clause in the outer query.
  */
  iParent = p->base + iFrom;
  iSub = pSub->base;
  substExprList(p->pEList, iParent, pSub->pEList, iSub);
................................................................................
  }else{
    substExpr(p->pWhere, iParent, pSub->pEList, iSub);
    if( pWhere ){
      p->pWhere = sqliteExpr(TK_AND, p->pWhere, pWhere, 0);
    }
  }
  p->isDistinct = p->isDistinct || pSub->isDistinct;








  if( pSrc->a[iFrom].pTab && pSrc->a[iFrom].pTab->isTransient ){
    sqliteDeleteTable(0, pSrc->a[iFrom].pTab);
  }
  pSrc->a[iFrom].pTab = pSubSrc->a[0].pTab;
  pSubSrc->a[0].pTab = 0;
  pSrc->a[iFrom].pSelect = pSubSrc->a[0].pSelect;
  pSubSrc->a[0].pSelect = 0;
................................................................................
    sqliteVdbeAddOp(v, OP_MoveTo, base, 0);
  }
  eList.nExpr = 1;
  memset(&eListItem, 0, sizeof(eListItem));
  eList.a = &eListItem;
  eList.a[0].pExpr = pExpr;
  cont = sqliteVdbeMakeLabel(v);
  selectInnerLoop(pParse, &eList, base, 1, 0, -1, eDest, iParm, cont, cont);
  sqliteVdbeResolveLabel(v, cont);
  sqliteVdbeAddOp(v, OP_Close, base, 0);
  return 1;
}

/*
** Generate code for the given SELECT statement.
................................................................................
  pWInfo = sqliteWhereBegin(pParse, p->base, pTabList, pWhere, 0);
  if( pWInfo==0 ) goto select_end;

  /* Use the standard inner loop if we are not dealing with
  ** aggregates
  */
  if( !isAgg ){
    if( selectInnerLoop(pParse, pEList, 0, 0, pOrderBy, distinct, eDest, iParm,
                    pWInfo->iContinue, pWInfo->iBreak) ){
       goto select_end;
    }
  }

  /* If we are dealing with aggregates, then to the special aggregate
  ** processing.  
  */
................................................................................
    int endagg = sqliteVdbeMakeLabel(v);
    int startagg;
    startagg = sqliteVdbeAddOp(v, OP_AggNext, 0, endagg);
    pParse->useAgg = 1;
    if( pHaving ){
      sqliteExprIfFalse(pParse, pHaving, startagg, 1);
    }
    if( selectInnerLoop(pParse, pEList, 0, 0, pOrderBy, distinct, eDest, iParm,
                    startagg, endagg) ){
      goto select_end;
    }
    sqliteVdbeAddOp(v, OP_Goto, 0, startagg);
    sqliteVdbeResolveLabel(v, endagg);
    sqliteVdbeAddOp(v, OP_Noop, 0, 0);
    pParse->useAgg = 0;
  }

  /* 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(v, pEList->nExpr);
  }


  /* Issue a null callback if that is what the user wants.
  */
  if( (pParse->db->flags & SQLITE_NullCallback)!=0 && eDest==SRT_Callback ){
    sqliteVdbeAddOp(v, OP_NullCallback, pEList->nExpr, 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 SELECT statements in SQLite.
**
** $Id: select.c,v 1.93 2002/06/14 22:38:42 drh Exp $
*/
#include "sqliteInt.h"

/*
** Allocate a new Select structure and return a pointer to that
** structure.
*/
................................................................................
**
** The pEList is used to determine the values for each column in the
** result row.  Except  if pEList==NULL, then we just read nColumn
** elements from the srcTab table.
*/
static int selectInnerLoop(
  Parse *pParse,          /* The parser context */
  Select *p,              /* The complete select statement being coded */
  ExprList *pEList,       /* List of values being extracted */
  int srcTab,             /* Pull data from this table */
  int nColumn,            /* Number of columns in the source table */
  ExprList *pOrderBy,     /* If not NULL, sort results using this key */
  int distinct,           /* If >=0, make sure results are distinct */
  int eDest,              /* How to dispose of the results */
  int iParm,              /* An argument to the disposal method */
  int iContinue,          /* Jump here to continue with next row */
  int iBreak              /* Jump here to break out of the inner loop */
){
  Vdbe *v = pParse->pVdbe;
  int i;
  if( v==0 ) return 0;

  /* If there was a LIMIT clause on the SELECT statement, then do the check
  ** to see if this row should be output.
  */
  if( pOrderBy==0 ){
    if( p->nOffset>0 ){
      sqliteVdbeAddOp(v, OP_LimitCk, 1, iContinue);
    }
    if( p->nLimit>0 ){
      sqliteVdbeAddOp(v, OP_LimitCk, 0, iBreak);
    }
  }

  /* Pull the requested columns.
  */
  if( pEList ){
    for(i=0; i<pEList->nExpr; i++){
      sqliteExprCode(pParse, pEList->a[i].pExpr);
    }
................................................................................
  if( eDest==SRT_Discard ){
    sqliteVdbeAddOp(v, OP_Pop, nColumn, 0);
  }else

  /* If none of the above, send the data to the callback function.
  */
  {
    assert( eDest==SRT_Callback );
    sqliteVdbeAddOp(v, OP_Callback, nColumn, 0);
  }
  return 0;
}

/*
** 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(Select *p, Vdbe *v, int nColumn){
  int end = sqliteVdbeMakeLabel(v);
  int addr;
  sqliteVdbeAddOp(v, OP_Sort, 0, 0);
  addr = sqliteVdbeAddOp(v, OP_SortNext, 0, end);
  if( p->nOffset>0 ){
    sqliteVdbeAddOp(v, OP_LimitCk, 1, addr);
  }
  if( p->nLimit>0 ){
    sqliteVdbeAddOp(v, OP_LimitCk, 0, end);
  }
  sqliteVdbeAddOp(v, OP_SortCallback, nColumn, 0);
  sqliteVdbeAddOp(v, OP_Goto, 0, addr);
  sqliteVdbeResolveLabel(v, end);
  sqliteVdbeAddOp(v, OP_SortReset, 0, 0);
}

/*
** Generate code that will tell the VDBE how many columns there
................................................................................
        if( eDest==SRT_Callback ){
          generateColumnNames(pParse, p->base, 0, p->pEList);
        }
        iBreak = sqliteVdbeMakeLabel(v);
        iCont = sqliteVdbeMakeLabel(v);
        sqliteVdbeAddOp(v, OP_Rewind, unionTab, iBreak);
        iStart = sqliteVdbeCurrentAddr(v);
        rc = selectInnerLoop(pParse, p, 0, unionTab, p->pEList->nExpr,
                             p->pOrderBy, -1, eDest, iParm, 
                             iCont, iBreak);
        if( rc ) return 1;
        sqliteVdbeResolveLabel(v, iCont);
        sqliteVdbeAddOp(v, OP_Next, unionTab, iStart);
        sqliteVdbeResolveLabel(v, iBreak);
        sqliteVdbeAddOp(v, OP_Close, unionTab, 0);
        if( p->pOrderBy ){
          generateSortTail(p, v, p->pEList->nExpr);
        }
      }
      break;
    }
    case TK_INTERSECT: {
      int tab1, tab2;
      int iCont, iBreak, iStart;
................................................................................
        generateColumnNames(pParse, p->base, 0, p->pEList);
      }
      iBreak = sqliteVdbeMakeLabel(v);
      iCont = sqliteVdbeMakeLabel(v);
      sqliteVdbeAddOp(v, OP_Rewind, tab1, iBreak);
      iStart = sqliteVdbeAddOp(v, OP_FullKey, tab1, 0);
      sqliteVdbeAddOp(v, OP_NotFound, tab2, iCont);
      rc = selectInnerLoop(pParse, p, 0, tab1, p->pEList->nExpr,
                             p->pOrderBy, -1, eDest, iParm, 
                             iCont, iBreak);
      if( rc ) return 1;
      sqliteVdbeResolveLabel(v, iCont);
      sqliteVdbeAddOp(v, OP_Next, tab1, iStart);
      sqliteVdbeResolveLabel(v, iBreak);
      sqliteVdbeAddOp(v, OP_Close, tab2, 0);
      sqliteVdbeAddOp(v, OP_Close, tab1, 0);
      if( p->pOrderBy ){
        generateSortTail(p, v, p->pEList->nExpr);
      }
      break;
    }
  }
  assert( p->pEList && pPrior->pEList );
  if( p->pEList->nExpr!=pPrior->pEList->nExpr ){
    sqliteSetString(&pParse->zErrMsg, "SELECTs to the left and right of ",
................................................................................
**   (5)  The subquery is not DISTINCT or the outer query does not use
**        aggregates.
**
**   (6)  The subquery does not use aggregates or the outer query is not
**        DISTINCT.
**
**   (7)  The subquery has a FROM clause.
**
**   (8)  The subquery does not use LIMIT or the outer query is not a join.
**
**   (9)  The subquery does not use LIMIT or the outer query does not use
**        aggregates.
**
**  (10)  The subquery does not use aggregates or the outer query does not
**        use LIMIT.
**
** In this routine, the "p" parameter is a pointer to the outer query.
** The subquery is p->pSrc->a[iFrom].  isAgg is true if the outer query
** uses aggregates and subqueryIsAgg is true if the subquery uses aggregates.
**
** If flattening is not attempted, this routine is a no-op and return 0.
** If flattening is attempted this routine returns 1.
................................................................................
  pSub = pSrc->a[iFrom].pSelect;
  assert( pSub!=0 );
  if( isAgg && subqueryIsAgg ) return 0;
  if( subqueryIsAgg && pSrc->nSrc>1 ) return 0;
  pSubSrc = pSub->pSrc;
  assert( pSubSrc );
  if( pSubSrc->nSrc!=1 ) return 0;
  if( (pSub->isDistinct || pSub->nLimit>=0) &&  (pSrc->nSrc>1 || isAgg) ){
     return 0;
  }
  if( (p->isDistinct || p->nLimit) && subqueryIsAgg ) return 0;

  /* If we reach this point, it means flattening is permitted for the
  ** i-th entry of the FROM clause in the outer query.
  */
  iParent = p->base + iFrom;
  iSub = pSub->base;
  substExprList(p->pEList, iParent, pSub->pEList, iSub);
................................................................................
  }else{
    substExpr(p->pWhere, iParent, pSub->pEList, iSub);
    if( pWhere ){
      p->pWhere = sqliteExpr(TK_AND, p->pWhere, pWhere, 0);
    }
  }
  p->isDistinct = p->isDistinct || pSub->isDistinct;
  if( pSub->nLimit>=0 ){
    if( p->nLimit<0 ){
      p->nLimit = pSub->nLimit;
    }else if( p->nLimit+p->nOffset > pSub->nLimit+pSub->nOffset ){
      p->nLimit = pSub->nLimit + pSub->nOffset - p->nOffset;
    }
  }
  p->nOffset += pSub->nOffset;
  if( pSrc->a[iFrom].pTab && pSrc->a[iFrom].pTab->isTransient ){
    sqliteDeleteTable(0, pSrc->a[iFrom].pTab);
  }
  pSrc->a[iFrom].pTab = pSubSrc->a[0].pTab;
  pSubSrc->a[0].pTab = 0;
  pSrc->a[iFrom].pSelect = pSubSrc->a[0].pSelect;
  pSubSrc->a[0].pSelect = 0;
................................................................................
    sqliteVdbeAddOp(v, OP_MoveTo, base, 0);
  }
  eList.nExpr = 1;
  memset(&eListItem, 0, sizeof(eListItem));
  eList.a = &eListItem;
  eList.a[0].pExpr = pExpr;
  cont = sqliteVdbeMakeLabel(v);
  selectInnerLoop(pParse, p, &eList, base, 1, 0, -1, eDest, iParm, cont, cont);
  sqliteVdbeResolveLabel(v, cont);
  sqliteVdbeAddOp(v, OP_Close, base, 0);
  return 1;
}

/*
** Generate code for the given SELECT statement.
................................................................................
  pWInfo = sqliteWhereBegin(pParse, p->base, pTabList, pWhere, 0);
  if( pWInfo==0 ) goto select_end;

  /* Use the standard inner loop if we are not dealing with
  ** aggregates
  */
  if( !isAgg ){
    if( selectInnerLoop(pParse, p, pEList, 0, 0, pOrderBy, distinct, eDest,
                    iParm, pWInfo->iContinue, pWInfo->iBreak) ){
       goto select_end;
    }
  }

  /* If we are dealing with aggregates, then to the special aggregate
  ** processing.  
  */
................................................................................
    int endagg = sqliteVdbeMakeLabel(v);
    int startagg;
    startagg = sqliteVdbeAddOp(v, OP_AggNext, 0, endagg);
    pParse->useAgg = 1;
    if( pHaving ){
      sqliteExprIfFalse(pParse, pHaving, startagg, 1);
    }
    if( selectInnerLoop(pParse, p, pEList, 0, 0, pOrderBy, distinct, eDest,
                    iParm, startagg, endagg) ){
      goto select_end;
    }
    sqliteVdbeAddOp(v, OP_Goto, 0, startagg);
    sqliteVdbeResolveLabel(v, endagg);
    sqliteVdbeAddOp(v, OP_Noop, 0, 0);
    pParse->useAgg = 0;
  }

  /* 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(p, v, pEList->nExpr);
  }


  /* Issue a null callback if that is what the user wants.
  */
  if( (pParse->db->flags & SQLITE_NullCallback)!=0 && eDest==SRT_Callback ){
    sqliteVdbeAddOp(v, OP_NullCallback, pEList->nExpr, 0);

** type to the other occurs as necessary.
** 
** Most of the code in this file is taken up by the sqliteVdbeExec()
** function which does the work of interpreting a VDBE program.
** But other routines are also provided to help in building up
** a program instruction by instruction.
**
** $Id: vdbe.c,v 1.155 2002/06/11 02:25:42 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

/*
** The following global variable is incremented every time a cursor
** moves, either by the OP_MoveTo or the OP_Next opcode.  The test
................................................................................
  "Add",               "AddImm",            "Subtract",          "Multiply",
  "Divide",            "Remainder",         "BitAnd",            "BitOr",
  "BitNot",            "ShiftLeft",         "ShiftRight",        "AbsValue",
  "Eq",                "Ne",                "Lt",                "Le",
  "Gt",                "Ge",                "IsNull",            "NotNull",
  "Negative",          "And",               "Or",                "Not",
  "Concat",            "Noop",              "Function",          "Limit",

};

/*
** Given the name of an opcode, return its number.  Return 0 if
** there is no match.
**
** This routine is used for testing and debugging.
................................................................................
*/
case OP_ColumnName: {
  p->azColName[pOp->p1] = pOp->p3 ? pOp->p3 : "";
  p->nCallback = 0;
  break;
}

/* Opcode: Callback P1 P2 *
**
** Pop P1 values off the stack and form them into an array.  Then
** invoke the callback function using the newly formed array as the
** 3rd parameter.
**
** If the offset counter (set by the OP_Limit opcode) is positive,
** then decrement the counter and do not invoke the callback.
** 
** If the callback is invoked, then after the callback returns
** decrement the limit counter.  When the limit counter reaches
** zero, jump to address P2.
*/
case OP_Callback: {
  int i = p->tos - pOp->p1 + 1;
  int j;
  VERIFY( if( i<0 ) goto not_enough_stack; )
  VERIFY( if( NeedStack(p, p->tos+2) ) goto no_mem; )
  for(j=i; j<=p->tos; j++){
................................................................................
      zStack[j] = 0;
    }else{
      if( Stringify(p, j) ) goto no_mem;
    }
  }
  zStack[p->tos+1] = 0;
  if( xCallback!=0 ){
    if( p->iOffset>0 ){
      p->iOffset--;
    }else{
      if( sqliteSafetyOff(db) ) goto abort_due_to_misuse; 
      if( xCallback(pArg, pOp->p1, &zStack[i], p->azColName)!=0 ){
        rc = SQLITE_ABORT;
      }
      if( sqliteSafetyOn(db) ) goto abort_due_to_misuse;
      p->nCallback++;
      if( p->iLimit>0 ){
        p->iLimit--;
        if( p->iLimit==0 ){
          pc = pOp->p2 - 1;
        }
      }
    }
  }
  PopStack(p, pOp->p1);
  if( sqlite_malloc_failed ) goto no_mem;
  break;
}

/* Opcode: NullCallback P1 * *
................................................................................
** of a SELECT statement.
*/
case OP_Limit: {
  p->iLimit = pOp->p1;
  p->iOffset = pOp->p2;
  break;
}






























/* Opcode: ListWrite * * *
**
** Write the integer on the top of the stack
** into the temporary storage list.
*/
case OP_ListWrite: {
................................................................................
    sqliteFree(pSorter);
  }else{
    pc = pOp->p2 - 1;
  }
  break;
}

/* Opcode: SortCallback P1 P2 *
**
** The top of the stack contains a callback record built using
** the SortMakeRec operation with the same P1 value as this
** instruction.  Pop this record from the stack and invoke the
** callback on it.
**
** If the offset counter (set by the OP_Limit opcode) is positive,
** then decrement the counter and do not invoke the callback.
** 
** If the callback is invoked, then after the callback returns
** decrement the limit counter.  When the limit counter reaches
** zero, jump to address P2.
*/
case OP_SortCallback: {
  int i = p->tos;
  VERIFY( if( i<0 ) goto not_enough_stack; )
  if( xCallback!=0 ){
    if( p->iOffset>0 ){
      p->iOffset--;
    }else{
      if( sqliteSafetyOff(db) ) goto abort_due_to_misuse;
      if( xCallback(pArg, pOp->p1, (char**)zStack[i], p->azColName)!=0 ){
        rc = SQLITE_ABORT;
      }
      if( sqliteSafetyOn(db) ) goto abort_due_to_misuse;
      p->nCallback++;
      if( p->iLimit>0 ){
        p->iLimit--;
        if( p->iLimit==0 ){
          pc = pOp->p2 - 1;
        }
      }
    }
    p->nCallback++;
  }
  POPSTACK;
  if( sqlite_malloc_failed ) goto no_mem;
  break;
}

** type to the other occurs as necessary.
** 
** Most of the code in this file is taken up by the sqliteVdbeExec()
** function which does the work of interpreting a VDBE program.
** But other routines are also provided to help in building up
** a program instruction by instruction.
**
** $Id: vdbe.c,v 1.156 2002/06/14 22:38:43 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

/*
** The following global variable is incremented every time a cursor
** moves, either by the OP_MoveTo or the OP_Next opcode.  The test
................................................................................
  "Add",               "AddImm",            "Subtract",          "Multiply",
  "Divide",            "Remainder",         "BitAnd",            "BitOr",
  "BitNot",            "ShiftLeft",         "ShiftRight",        "AbsValue",
  "Eq",                "Ne",                "Lt",                "Le",
  "Gt",                "Ge",                "IsNull",            "NotNull",
  "Negative",          "And",               "Or",                "Not",
  "Concat",            "Noop",              "Function",          "Limit",
  "LimitCk",
};

/*
** Given the name of an opcode, return its number.  Return 0 if
** there is no match.
**
** This routine is used for testing and debugging.
................................................................................
*/
case OP_ColumnName: {
  p->azColName[pOp->p1] = pOp->p3 ? pOp->p3 : "";
  p->nCallback = 0;
  break;
}

/* Opcode: Callback P1 * *
**
** Pop P1 values off the stack and form them into an array.  Then
** invoke the callback function using the newly formed array as the
** 3rd parameter.







*/
case OP_Callback: {
  int i = p->tos - pOp->p1 + 1;
  int j;
  VERIFY( if( i<0 ) goto not_enough_stack; )
  VERIFY( if( NeedStack(p, p->tos+2) ) goto no_mem; )
  for(j=i; j<=p->tos; j++){
................................................................................
      zStack[j] = 0;
    }else{
      if( Stringify(p, j) ) goto no_mem;
    }
  }
  zStack[p->tos+1] = 0;
  if( xCallback!=0 ){



    if( sqliteSafetyOff(db) ) goto abort_due_to_misuse; 
    if( xCallback(pArg, pOp->p1, &zStack[i], p->azColName)!=0 ){
      rc = SQLITE_ABORT;
    }
    if( sqliteSafetyOn(db) ) goto abort_due_to_misuse;
    p->nCallback++;







  }
  PopStack(p, pOp->p1);
  if( sqlite_malloc_failed ) goto no_mem;
  break;
}

/* Opcode: NullCallback P1 * *
................................................................................
** of a SELECT statement.
*/
case OP_Limit: {
  p->iLimit = pOp->p1;
  p->iOffset = pOp->p2;
  break;
}

/* Opcode: LimitCk P1 P2 *
**
** If P1 is 1, then check to see if the offset counter (set by the
** P2 argument of OP_Limit) is positive.  If the offset counter is
** positive then decrement the counter and jump immediately to P2.
** Otherwise fall straight through.
**
** If P1 is 0, then check the value of the limit counter (set by the
** P1 argument of OP_Limit).  If the limit counter is negative or
** zero then jump immedately to P2.  Otherwise decrement the limit
** counter and fall through.
*/
case OP_LimitCk: {
  if( pOp->p1 ){
    if( p->iOffset ){
      p->iOffset--;
      pc = pOp->p2 - 1;
    }
  }else{
    if( p->iLimit>0 ){
      p->iLimit--;
    }else{
      pc = pOp->p2 - 1;
    }
  }
  break;
}


/* Opcode: ListWrite * * *
**
** Write the integer on the top of the stack
** into the temporary storage list.
*/
case OP_ListWrite: {
................................................................................
    sqliteFree(pSorter);
  }else{
    pc = pOp->p2 - 1;
  }
  break;
}

/* Opcode: SortCallback P1 * *
**
** The top of the stack contains a callback record built using
** the SortMakeRec operation with the same P1 value as this
** instruction.  Pop this record from the stack and invoke the
** callback on it.







*/
case OP_SortCallback: {
  int i = p->tos;
  VERIFY( if( i<0 ) goto not_enough_stack; )
  if( xCallback!=0 ){



    if( sqliteSafetyOff(db) ) goto abort_due_to_misuse;
    if( xCallback(pArg, pOp->p1, (char**)zStack[i], p->azColName)!=0 ){
      rc = SQLITE_ABORT;
    }
    if( sqliteSafetyOn(db) ) goto abort_due_to_misuse;








    p->nCallback++;
  }
  POPSTACK;
  if( sqlite_malloc_failed ) goto no_mem;
  break;
}

*************************************************************************
** Header file for the Virtual DataBase Engine (VDBE)
**
** This header defines the interface to the virtual database engine
** or VDBE.  The VDBE implements an abstract machine that runs a
** simple program to access and modify the underlying database.
**
** $Id: vdbe.h,v 1.54 2002/06/08 23:25:09 drh Exp $
*/
#ifndef _SQLITE_VDBE_H_
#define _SQLITE_VDBE_H_
#include <stdio.h>

/*
** A single VDBE is an opaque structure named "Vdbe".  Only routines
................................................................................
#define OP_Or                115
#define OP_Not               116
#define OP_Concat            117
#define OP_Noop              118
#define OP_Function          119

#define OP_Limit             120



#define OP_MAX               120

/*
** Prototypes for the VDBE interface.  See comments on the implementation
** for a description of what each of these routines does.
*/
Vdbe *sqliteVdbeCreate(sqlite*);
void sqliteVdbeCreateCallback(Vdbe*, int*);

*************************************************************************
** Header file for the Virtual DataBase Engine (VDBE)
**
** This header defines the interface to the virtual database engine
** or VDBE.  The VDBE implements an abstract machine that runs a
** simple program to access and modify the underlying database.
**
** $Id: vdbe.h,v 1.55 2002/06/14 22:38:43 drh Exp $
*/
#ifndef _SQLITE_VDBE_H_
#define _SQLITE_VDBE_H_
#include <stdio.h>

/*
** A single VDBE is an opaque structure named "Vdbe".  Only routines
................................................................................
#define OP_Or                115
#define OP_Not               116
#define OP_Concat            117
#define OP_Noop              118
#define OP_Function          119

#define OP_Limit             120
#define OP_LimitCk           121


#define OP_MAX               121

/*
** Prototypes for the VDBE interface.  See comments on the implementation
** for a description of what each of these routines does.
*/
Vdbe *sqliteVdbeCreate(sqlite*);
void sqliteVdbeCreateCallback(Vdbe*, int*);

**    May you share freely, never taking more than you give.
**
*************************************************************************
** This module contains C code that generates VDBE code used to process
** the WHERE clause of SQL statements.  Also found here are subroutines
** to generate VDBE code to evaluate expressions.
**
** $Id: where.c,v 1.51 2002/06/14 20:58:45 drh Exp $
*/
#include "sqliteInt.h"

/*
** The query generator uses an array of instances of this structure to
** help it analyze the subexpressions of the WHERE clause.  Each WHERE
** clause subexpression is separated from the others by an AND operator.
................................................................................
  pWInfo->iBreak = sqliteVdbeMakeLabel(v);

  /* Special case: a WHERE clause that is constant.  Evaluate the
  ** expression and either jump over all of the code or fall thru.
  */
  if( pWhere && sqliteExprIsConstant(pWhere) ){
    sqliteExprIfFalse(pParse, pWhere, pWInfo->iBreak, 1);

  }

  /* Split the WHERE clause into as many as 32 separate subexpressions
  ** where each subexpression is separated by an AND operator.  Any additional
  ** subexpressions are attached in the aExpr[32] and will not enter
  ** into the query optimizer computations.  32 is chosen as the cutoff
  ** since that is the number of bits in an integer that we use for an

**    May you share freely, never taking more than you give.
**
*************************************************************************
** This module contains C code that generates VDBE code used to process
** the WHERE clause of SQL statements.  Also found here are subroutines
** to generate VDBE code to evaluate expressions.
**
** $Id: where.c,v 1.52 2002/06/14 22:38:43 drh Exp $
*/
#include "sqliteInt.h"

/*
** The query generator uses an array of instances of this structure to
** help it analyze the subexpressions of the WHERE clause.  Each WHERE
** clause subexpression is separated from the others by an AND operator.
................................................................................
  pWInfo->iBreak = sqliteVdbeMakeLabel(v);

  /* Special case: a WHERE clause that is constant.  Evaluate the
  ** expression and either jump over all of the code or fall thru.
  */
  if( pWhere && sqliteExprIsConstant(pWhere) ){
    sqliteExprIfFalse(pParse, pWhere, pWInfo->iBreak, 1);
    pWhere = 0;
  }

  /* Split the WHERE clause into as many as 32 separate subexpressions
  ** where each subexpression is separated by an AND operator.  Any additional
  ** subexpressions are attached in the aExpr[32] and will not enter
  ** into the query optimizer computations.  32 is chosen as the cutoff
  ** since that is the number of bits in an integer that we use for an

#    May you share freely, never taking more than you give.
#
#***********************************************************************
# This file implements regression tests for SQLite library.  The
# focus of this file is testing the LIMIT ... OFFSET ... clause
#  of SELECT statements.
#
# $Id: limit.test,v 1.2 2002/05/24 16:14:16 drh Exp $

set testdir [file dirname $argv0]
source $testdir/tester.tcl

# Build some test data
#
set fd [open data1.txt w]
................................................................................
} {}
do_test limit-1.6 {
  execsql {SELECT * FROM t1 AS a, t1 AS b ORDER BY a.x, b.x LIMIT 5}
} {0 5 0 5 0 5 1 5 0 5 2 5 0 5 3 5 0 5 4 5}
do_test limit-1.7 {
  execsql {SELECT * FROM t1 AS a, t1 AS b ORDER BY a.x, b.x LIMIT 5 OFFSET 32}
} {1 5 0 5 1 5 1 5 1 5 2 5 1 5 3 5 1 5 4 5}




















finish_test

#    May you share freely, never taking more than you give.
#
#***********************************************************************
# This file implements regression tests for SQLite library.  The
# focus of this file is testing the LIMIT ... OFFSET ... clause
#  of SELECT statements.
#
# $Id: limit.test,v 1.3 2002/06/14 22:38:43 drh Exp $

set testdir [file dirname $argv0]
source $testdir/tester.tcl

# Build some test data
#
set fd [open data1.txt w]
................................................................................
} {}
do_test limit-1.6 {
  execsql {SELECT * FROM t1 AS a, t1 AS b ORDER BY a.x, b.x LIMIT 5}
} {0 5 0 5 0 5 1 5 0 5 2 5 0 5 3 5 0 5 4 5}
do_test limit-1.7 {
  execsql {SELECT * FROM t1 AS a, t1 AS b ORDER BY a.x, b.x LIMIT 5 OFFSET 32}
} {1 5 0 5 1 5 1 5 1 5 2 5 1 5 3 5 1 5 4 5}

do_test limit-2.1 {
  execsql {
    CREATE VIEW v1 AS SELECT * FROM t1 LIMIT 2;
    SELECT count(*) FROM (SELECT * FROM v1);
  }
} 2
do_test limit-2.2 {
  execsql {
    CREATE TABLE t2 AS SELECT * FROM t1 LIMIT 2;
    SELECT count(*) FROM t2;
  }
} 2
do_test limit-2.3 {
  execsql {
    SELECT count(*) FROM t1 WHERE rowid IN (SELECT rowid FROM t1 LIMIT 2);
  }
} 2


finish_test

#    May you find forgiveness for yourself and forgive others.
#    May you share freely, never taking more than you give.
#
#***********************************************************************
# This file implements regression tests for SQLite library.  The
# focus of this file is testing the use of indices in WHERE clases.
#
# $Id: where.test,v 1.7 2002/06/09 01:55:20 drh Exp $

set testdir [file dirname $argv0]
source $testdir/tester.tcl

# Build some test data
#
do_test where-1.0 {
................................................................................
    SELECT * FROM t1 WHERE 0
  }
} {0}
do_test where-4.2 {
  count {
    SELECT * FROM t1 WHERE 1 LIMIT 1
  }
} {1 0 4 0}
do_test where-4.3 {
  execsql {
    SELECT 99 WHERE 0
  }
} {}
do_test where-4.4 {
  execsql {

#    May you find forgiveness for yourself and forgive others.
#    May you share freely, never taking more than you give.
#
#***********************************************************************
# This file implements regression tests for SQLite library.  The
# focus of this file is testing the use of indices in WHERE clases.
#
# $Id: where.test,v 1.8 2002/06/14 22:38:43 drh Exp $

set testdir [file dirname $argv0]
source $testdir/tester.tcl

# Build some test data
#
do_test where-1.0 {
................................................................................
    SELECT * FROM t1 WHERE 0
  }
} {0}
do_test where-4.2 {
  count {
    SELECT * FROM t1 WHERE 1 LIMIT 1
  }
} {1 0 4 1}
do_test where-4.3 {
  execsql {
    SELECT 99 WHERE 0
  }
} {}
do_test where-4.4 {
  execsql {