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Overview
Comment:Make the LIMIT clause work even if the destination of the SELECT is something other than a callback. (Ticket #66) (CVS 619)
Downloads: Tarball | ZIP archive | SQL archive
Timelines: family | ancestors | descendants | both | trunk
Files: files | file ages | folders
SHA1: 699cf362083043615eb88635a228bfa46a315c9c
User & Date: drh 2002-06-14 22:38:42
Context
2002-06-16
04:54
Changed sqlite_mprintf_str to allow a NULL string parameter. Command template now is cmd FORMAT INT INT ?STRING?. When STRING omitted a NULL is passed to sqlite_mprintf. (CVS 620) check-in: 8bc71157 user: chw tags: trunk
2002-06-14
22:38
Make the LIMIT clause work even if the destination of the SELECT is something other than a callback. (Ticket #66) (CVS 619) check-in: 699cf362 user: drh tags: trunk
20:58
Improvements to comments. No code changes. (CVS 618) check-in: 7e10e60b user: drh tags: trunk
Changes
Hide Diffs Unified Diffs Ignore Whitespace Patch

Changes to src/select.c.

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**    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);







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**    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);

Changes to src/vdbe.c.

26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
....
1076
1077
1078
1079
1080
1081
1082

1083
1084
1085
1086
1087
1088
1089
....
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
....
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
....
3912
3913
3914
3915
3916
3917
3918





























3919
3920
3921
3922
3923
3924
3925
....
4203
4204
4205
4206
4207
4208
4209
4210
4211
4212
4213
4214
4215
4216
4217
4218
4219
4220
4221
4222
4223
4224
4225
4226
4227
4228
4229
4230
4231
4232
4233
4234
4235
4236
4237
4238
4239
4240
4241
4242
4243
4244
4245
4246
4247
4248
4249
4250
** 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;
}








|







 







>







 







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<
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<
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<
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<







26
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38
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40
....
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
....
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593







1594
1595
1596
1597
1598
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1600
....
1602
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1605
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1607
1608



1609
1610
1611
1612
1613
1614







1615
1616
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1618
1619
1620
1621
....
3896
3897
3898
3899
3900
3901
3902
3903
3904
3905
3906
3907
3908
3909
3910
3911
3912
3913
3914
3915
3916
3917
3918
3919
3920
3921
3922
3923
3924
3925
3926
3927
3928
3929
3930
3931
3932
3933
3934
3935
3936
3937
3938
....
4216
4217
4218
4219
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4221
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4224
4225
4226
4227
4228







4229
4230
4231
4232
4233



4234
4235
4236
4237
4238








4239
4240
4241
4242
4243
4244
4245
** 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;
}

Changes to src/vdbe.h.

11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
...
200
201
202
203
204
205
206

207
208
209
210
211
212
213
214
215
216
*************************************************************************
** 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*);







|







 







>


|







11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
...
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
*************************************************************************
** 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*);

Changes to src/where.c.

9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
...
254
255
256
257
258
259
260

261
262
263
264
265
266
267
**    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







|







 







>







9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
...
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
**    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

Changes to test/limit.test.

8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
..
51
52
53
54
55
56
57


















58
59
60
#    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







|







 







>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>



8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
..
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
#    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

Changes to test/where.test.

7
8
9
10
11
12
13
14
15
16
17
18
19
20
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#    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 {







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#    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 {