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Comment:Multiplying NULL by zero gives NULL, not zero. I misread the test data and coded it wrong. This check-in fixes the problem. (CVS 601)
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SHA1: df9cc852ad02dbec5558d3915a0303f7e7b79b2b
User & Date: drh 2002-06-01 21:41:10.000
Context
2002-06-02
16:09
Enhance the ORDER BY clause so that an integer term means to sort by the corresponding column. (CVS 602) (check-in: 7acbf84b49 user: drh tags: trunk)
2002-06-01
21:41
Multiplying NULL by zero gives NULL, not zero. I misread the test data and coded it wrong. This check-in fixes the problem. (CVS 601) (check-in: df9cc852ad user: drh tags: trunk)
2002-05-31
15:51
Refinements to NULL processing: NULLs are indistinct for DISTINCT and UNION. Multiplying a NULL by zero yields zero. In a CASE expression, a NULL comparison is considered false, not NULL. With these changes, NULLs in SQLite now work the same as in PostgreSQL and in Oracle. (CVS 600) (check-in: da61aa1d23 user: drh tags: trunk)
Changes
Unified Diff Ignore Whitespace Patch
Changes to src/vdbe.c.
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** 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 1.151 2002/05/31 15:51:26 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








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** 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 1.152 2002/06/01 21:41:10 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
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case OP_Multiply:
case OP_Divide:
case OP_Remainder: {
  int tos = p->tos;
  int nos = tos - 1;
  VERIFY( if( nos<0 ) goto not_enough_stack; )
  if( ((aStack[tos].flags | aStack[nos].flags) & STK_Null)!=0 ){
    int resultType = STK_Null;
    if( pOp->opcode==OP_Multiply ){
      /* Special case: multiplying NULL by zero gives a zero result, not a
      ** NULL result as it would normally. */
      if( (aStack[tos].flags & (STK_Int|STK_Real))!=0
              || ((aStack[tos].flags & STK_Str)!=0 && isNumber(zStack[tos])) ){
        Integerify(p,tos);
        if( aStack[tos].i==0 ){
          resultType = STK_Int;
          aStack[nos].i = 0;
        }
      }else if( (aStack[nos].flags & (STK_Int|STK_Real))!=0
              || ((aStack[nos].flags & STK_Str)!=0 && isNumber(zStack[nos])) ){
        Integerify(p,nos);
        if( aStack[nos].i==0 ){
          resultType = STK_Int;
        }
      }
    }
    POPSTACK;
    Release(p, nos);
    aStack[nos].flags = resultType;
  }else if( (aStack[tos].flags & aStack[nos].flags & STK_Int)==STK_Int ){
    int a, b;
    a = aStack[tos].i;
    b = aStack[nos].i;
    switch( pOp->opcode ){
      case OP_Add:         b += a;       break;
      case OP_Subtract:    b -= a;       break;








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case OP_Multiply:
case OP_Divide:
case OP_Remainder: {
  int tos = p->tos;
  int nos = tos - 1;
  VERIFY( if( nos<0 ) goto not_enough_stack; )
  if( ((aStack[tos].flags | aStack[nos].flags) & STK_Null)!=0 ){



















    POPSTACK;
    Release(p, nos);
    aStack[nos].flags = STK_Null;
  }else if( (aStack[tos].flags & aStack[nos].flags & STK_Int)==STK_Int ){
    int a, b;
    a = aStack[tos].i;
    b = aStack[nos].i;
    switch( pOp->opcode ){
      case OP_Add:         b += a;       break;
      case OP_Subtract:    b -= a;       break;
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Changes to test/null.test.
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    select ifnull(a+b,99) from t1;
  }
} {1 2 4 5 99 99 99}
do_test null-1.2 {
  execsql {
    select ifnull(b*c,99) from t1;
  }
} {0 0 0 1 0 99 99}
do_test null-1.2.1 {
  execsql {
    select ifnull(c*b,99) from t1;
  }
} {0 0 0 1 0 99 99}

# Check to see how the CASE expression handles NULL values.  The
# first WHEN for which the test expression is TRUE is selected.
# FALSE and UNKNOWN test expressions are skipped.
#
do_test null-2.1 {
  execsql {








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    select ifnull(a+b,99) from t1;
  }
} {1 2 4 5 99 99 99}
do_test null-1.2 {
  execsql {
    select ifnull(b*c,99) from t1;
  }
} {0 0 0 1 99 99 99}






# Check to see how the CASE expression handles NULL values.  The
# first WHEN for which the test expression is TRUE is selected.
# FALSE and UNKNOWN test expressions are skipped.
#
do_test null-2.1 {
  execsql {
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