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Overview
Comment:Change functions to handle NULLs correctly. Added the NULLIF() function. (CVS 590)
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SHA1:46ce1a9ab6e527958ebc757fa2175c488299cd84
User & Date: drh 2002-05-26 21:34:58
Context
2002-05-26
23:24
Require the INSTEAD OF syntax to create triggers on database views. (CVS 591) check-in: d9e48cd5 user: danielk1977 tags: trunk
21:34
Change functions to handle NULLs correctly. Added the NULLIF() function. (CVS 590) check-in: 46ce1a9a user: drh tags: trunk
20:54
NULL values are distinct. A comparison involving a NULL is always false. Operations on a NULL value yield a NULL result. This change makes SQLite operate more like the SQL spec, but it may break existing applications that assumed the old behavior. All the old tests pass but we still need to add new tests to better verify the new behavior. Fix for ticket #44. (CVS 589) check-in: 90511737 user: drh tags: trunk
Changes
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Changes to src/func.c.

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** This file contains the C functions that implement various SQL
** functions of SQLite.  
**
** There is only one exported symbol in this file - the function
** sqliteRegisterBuildinFunctions() found at the bottom of the file.
** All other code has file scope.
**
** $Id: func.c,v 1.16 2002/04/20 14:24:42 drh Exp $
*/
#include <ctype.h>
#include <math.h>
#include <stdlib.h>
#include <assert.h>
#include "sqliteInt.h"

................................................................................
*/
static void minFunc(sqlite_func *context, int argc, const char **argv){
  const char *zBest; 
  int i;

  if( argc==0 ) return;
  zBest = argv[0];

  for(i=1; i<argc; i++){

    if( sqliteCompare(argv[i], zBest)<0 ){
      zBest = argv[i];
    }
  }
  sqlite_set_result_string(context, zBest, -1);
}
static void maxFunc(sqlite_func *context, int argc, const char **argv){
  const char *zBest; 
  int i;

  if( argc==0 ) return;
  zBest = argv[0];

  for(i=1; i<argc; i++){

    if( sqliteCompare(argv[i], zBest)>0 ){
      zBest = argv[i];
    }
  }
  sqlite_set_result_string(context, zBest, -1);
}

................................................................................
*/
static void lengthFunc(sqlite_func *context, int argc, const char **argv){
  const char *z;
  int len;

  assert( argc==1 );
  z = argv[0];
  if( z==0 ){
    len = 0;
  }else{
#ifdef SQLITE_UTF8
    for(len=0; *z; z++){ if( (0xc0&*z)!=0x80 ) len++; }
#else
    len = strlen(z);
#endif
  }
  sqlite_set_result_int(context, len);
}

/*
** Implementation of the abs() function
*/
static void absFunc(sqlite_func *context, int argc, const char **argv){
  const char *z;
  assert( argc==1 );
  z = argv[0];

  if( z && z[0]=='-' && isdigit(z[1]) ) z++;
  sqlite_set_result_string(context, z, -1);
}

/*
** Implementation of the substr() function
*/
static void substrFunc(sqlite_func *context, int argc, const char **argv){
................................................................................
** Implementation of the round() function
*/
static void roundFunc(sqlite_func *context, int argc, const char **argv){
  int n;
  double r;
  char zBuf[100];
  assert( argc==1 || argc==2 );

  n = argc==2 && argv[1] ? atoi(argv[1]) : 0;
  if( n>30 ) n = 30;
  if( n<0 ) n = 0;
  r = argv[0] ? atof(argv[0]) : 0.0;
  sprintf(zBuf,"%.*f",n,r);
  sqlite_set_result_string(context, zBuf, -1);
}

/*
** Implementation of the upper() and lower() SQL functions.
*/
................................................................................
** string and the second argument is the pattern.  So, the SQL statements:
**
**       A LIKE B
**
** is implemented as like(A,B).
*/
static void likeFunc(sqlite_func *context, int arg, const char **argv){
  sqlite_set_result_int(context, 
     sqliteLikeCompare(argv[0] ? argv[0] : "",argv[1] ? argv[1] : ""));
}

/*
** Implementation of the glob() SQL function.  This function implements
** the build-in GLOB operator.  The first argument to the function is the
** string and the second argument is the pattern.  So, the SQL statements:
**
**       A GLOB B
**
** is implemented as glob(A,B).
*/
static void globFunc(sqlite_func *context, int arg, const char **argv){

  sqlite_set_result_int(context,
    sqliteGlobCompare(argv[0] ? argv[0] : "",argv[1] ? argv[1] : ""));











}

/*
** An instance of the following structure holds the context of a
** sum() or avg() aggregate computation.
*/
typedef struct SumCtx SumCtx;
................................................................................

/*
** This function tracks state information for the min() and max()
** aggregate functions.
*/
typedef struct MinMaxCtx MinMaxCtx;
struct MinMaxCtx {

  char *z;         /* The best so far */
  char zBuf[28];   /* Space that can be used for storage */
};

/*
** Routines to implement min() and max() aggregate functions.
*/
static void minStep(sqlite_func *context, int argc, const char **argv){
  MinMaxCtx *p;
  p = sqlite_aggregate_context(context, sizeof(*p));
  if( p==0 || argc<1 ) return;




  if( sqlite_aggregate_count(context)==1 || sqliteCompare(argv[0],p->z)<0 ){

    if( p->z && p->z!=p->zBuf ){
      sqliteFree(p->z);
    }
    if( argv[0] ){
      int len = strlen(argv[0]);
      if( len < sizeof(p->zBuf) ){
        p->z = p->zBuf;
      }else{
        p->z = sqliteMalloc( len+1 );
        if( p->z==0 ) return;
      }
      strcpy(p->z, argv[0]);
    }else{
      p->z = 0;
    }
  }
}
static void maxStep(sqlite_func *context, int argc, const char **argv){
  MinMaxCtx *p;
  p = sqlite_aggregate_context(context, sizeof(*p));
  if( p==0 || argc<1 ) return;




  if( sqlite_aggregate_count(context)==1 || sqliteCompare(argv[0],p->z)>0 ){

    if( p->z && p->z!=p->zBuf ){
      sqliteFree(p->z);
    }
    if( argv[0] ){
      int len = strlen(argv[0]);
      if( len < sizeof(p->zBuf) ){
        p->z = p->zBuf;
      }else{
        p->z = sqliteMalloc( len+1 );
        if( p->z==0 ) return;
      }
      strcpy(p->z, argv[0]);
    }else{
      p->z = 0;
    }
  }
}
static void minMaxFinalize(sqlite_func *context){
  MinMaxCtx *p;
  p = sqlite_aggregate_context(context, sizeof(*p));
  if( p && p->z ){
    sqlite_set_result_string(context, p->z, strlen(p->z));
  }
  if( p && p->z && p->z!=p->zBuf ){
    sqliteFree(p->z);
  }
}

................................................................................
    { "lower",      1, lowerFunc  },
    { "coalesce",  -1, ifnullFunc },
    { "coalesce",   0, 0          },
    { "coalesce",   1, 0          },
    { "random",    -1, randomFunc },
    { "like",       2, likeFunc   },
    { "glob",       2, globFunc   },

  };
  static struct {
    char *zName;
    int nArg;
    void (*xStep)(sqlite_func*,int,const char**);
    void (*xFinalize)(sqlite_func*);
  } aAggs[] = {







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** This file contains the C functions that implement various SQL
** functions of SQLite.  
**
** There is only one exported symbol in this file - the function
** sqliteRegisterBuildinFunctions() found at the bottom of the file.
** All other code has file scope.
**
** $Id: func.c,v 1.17 2002/05/26 21:34:58 drh Exp $
*/
#include <ctype.h>
#include <math.h>
#include <stdlib.h>
#include <assert.h>
#include "sqliteInt.h"

................................................................................
*/
static void minFunc(sqlite_func *context, int argc, const char **argv){
  const char *zBest; 
  int i;

  if( argc==0 ) return;
  zBest = argv[0];
  if( zBest==0 ) return;
  for(i=1; i<argc; i++){
    if( argv[i]==0 ) return;
    if( sqliteCompare(argv[i], zBest)<0 ){
      zBest = argv[i];
    }
  }
  sqlite_set_result_string(context, zBest, -1);
}
static void maxFunc(sqlite_func *context, int argc, const char **argv){
  const char *zBest; 
  int i;

  if( argc==0 ) return;
  zBest = argv[0];
  if( zBest==0 ) return;
  for(i=1; i<argc; i++){
    if( argv[i]==0 ) return;
    if( sqliteCompare(argv[i], zBest)>0 ){
      zBest = argv[i];
    }
  }
  sqlite_set_result_string(context, zBest, -1);
}

................................................................................
*/
static void lengthFunc(sqlite_func *context, int argc, const char **argv){
  const char *z;
  int len;

  assert( argc==1 );
  z = argv[0];
  if( z==0 ) return;


#ifdef SQLITE_UTF8
  for(len=0; *z; z++){ if( (0xc0&*z)!=0x80 ) len++; }
#else
  len = strlen(z);
#endif

  sqlite_set_result_int(context, len);
}

/*
** Implementation of the abs() function
*/
static void absFunc(sqlite_func *context, int argc, const char **argv){
  const char *z;
  assert( argc==1 );
  z = argv[0];
  if( z==0 ) return;
  if( z[0]=='-' && isdigit(z[1]) ) z++;
  sqlite_set_result_string(context, z, -1);
}

/*
** Implementation of the substr() function
*/
static void substrFunc(sqlite_func *context, int argc, const char **argv){
................................................................................
** Implementation of the round() function
*/
static void roundFunc(sqlite_func *context, int argc, const char **argv){
  int n;
  double r;
  char zBuf[100];
  assert( argc==1 || argc==2 );
  if( argv[0]==0 || (argc==2 && argv[1]==0) ) return;
  n = argc==2 ? atoi(argv[1]) : 0;
  if( n>30 ) n = 30;
  if( n<0 ) n = 0;
  r = atof(argv[0]);
  sprintf(zBuf,"%.*f",n,r);
  sqlite_set_result_string(context, zBuf, -1);
}

/*
** Implementation of the upper() and lower() SQL functions.
*/
................................................................................
** string and the second argument is the pattern.  So, the SQL statements:
**
**       A LIKE B
**
** is implemented as like(A,B).
*/
static void likeFunc(sqlite_func *context, int arg, const char **argv){
  if( argv[0]==0 || argv[1]==0 ) return;
  sqlite_set_result_int(context, sqliteLikeCompare(argv[0], argv[1]));
}

/*
** Implementation of the glob() SQL function.  This function implements
** the build-in GLOB operator.  The first argument to the function is the
** string and the second argument is the pattern.  So, the SQL statements:
**
**       A GLOB B
**
** is implemented as glob(A,B).
*/
static void globFunc(sqlite_func *context, int arg, const char **argv){
  if( argv[0]==0 || argv[1]==0 ) return;
  sqlite_set_result_int(context, sqliteGlobCompare(argv[0], argv[1]));

}

/*
** Implementation of the NULLIF(x,y) function.  The result is the first
** argument if the arguments are different.  The result is NULL if the
** arguments are equal to each other.
*/
static void nullifFunc(sqlite_func *context, int argc, const char **argv){
  if( argv[0]!=0 && sqliteCompare(argv[0],argv[1])!=0 ){
    sqlite_set_result_string(context, argv[0], -1);
  }
}

/*
** An instance of the following structure holds the context of a
** sum() or avg() aggregate computation.
*/
typedef struct SumCtx SumCtx;
................................................................................

/*
** This function tracks state information for the min() and max()
** aggregate functions.
*/
typedef struct MinMaxCtx MinMaxCtx;
struct MinMaxCtx {
  int isNull;      /* True if the result should be NULL */
  char *z;         /* The best so far */
  char zBuf[28];   /* Space that can be used for storage */
};

/*
** Routines to implement min() and max() aggregate functions.
*/
static void minStep(sqlite_func *context, int argc, const char **argv){
  MinMaxCtx *p;
  p = sqlite_aggregate_context(context, sizeof(*p));
  if( p==0 || argc<1 ) return;
  if( argv[0]==0 || p->isNull ){
    p->isNull = 1;
    return;
  }
  if( sqlite_aggregate_count(context)==1 || sqliteCompare(argv[0],p->z)<0 ){
    int len;
    if( p->z && p->z!=p->zBuf ){
      sqliteFree(p->z);
    }

    len = strlen(argv[0]);
    if( len < sizeof(p->zBuf) ){
      p->z = p->zBuf;
    }else{
      p->z = sqliteMalloc( len+1 );
      if( p->z==0 ) return;
    }
    strcpy(p->z, argv[0]);



  }
}
static void maxStep(sqlite_func *context, int argc, const char **argv){
  MinMaxCtx *p;
  p = sqlite_aggregate_context(context, sizeof(*p));
  if( p==0 || argc<1 ) return;
  if( argv[0]==0 || p->isNull ){
    p->isNull = 1;
    return;
  }
  if( sqlite_aggregate_count(context)==1 || sqliteCompare(argv[0],p->z)>0 ){
    int len;
    if( p->z && p->z!=p->zBuf ){
      sqliteFree(p->z);
    }

    len = strlen(argv[0]);
    if( len < sizeof(p->zBuf) ){
      p->z = p->zBuf;
    }else{
      p->z = sqliteMalloc( len+1 );
      if( p->z==0 ) return;
    }
    strcpy(p->z, argv[0]);



  }
}
static void minMaxFinalize(sqlite_func *context){
  MinMaxCtx *p;
  p = sqlite_aggregate_context(context, sizeof(*p));
  if( p && p->z && !p->isNull ){
    sqlite_set_result_string(context, p->z, strlen(p->z));
  }
  if( p && p->z && p->z!=p->zBuf ){
    sqliteFree(p->z);
  }
}

................................................................................
    { "lower",      1, lowerFunc  },
    { "coalesce",  -1, ifnullFunc },
    { "coalesce",   0, 0          },
    { "coalesce",   1, 0          },
    { "random",    -1, randomFunc },
    { "like",       2, likeFunc   },
    { "glob",       2, globFunc   },
    { "nullif",     2, nullifFunc },
  };
  static struct {
    char *zName;
    int nArg;
    void (*xStep)(sqlite_func*,int,const char**);
    void (*xFinalize)(sqlite_func*);
  } aAggs[] = {

Changes to src/util.c.

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**
*************************************************************************
** Utility functions used throughout sqlite.
**
** This file contains functions for allocating memory, comparing
** strings, and stuff like that.
**
** $Id: util.c,v 1.43 2002/05/10 13:14:07 drh Exp $
*/
#include "sqliteInt.h"
#include <stdarg.h>
#include <ctype.h>

/*
** If malloc() ever fails, this global variable gets set to 1.
................................................................................
** order is a little bit different.  See sqliteSortCompare below
** for additional information.
*/
int sqliteCompare(const char *atext, const char *btext){
  int result;
  int isNumA, isNumB;
  if( atext==0 ){
    return -(btext!=0);
  }else if( btext==0 ){
    return 1;
  }
  isNumA = sqliteIsNumber(atext);
  isNumB = sqliteIsNumber(btext);
  if( isNumA ){
    if( !isNumB ){







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**
*************************************************************************
** Utility functions used throughout sqlite.
**
** This file contains functions for allocating memory, comparing
** strings, and stuff like that.
**
** $Id: util.c,v 1.44 2002/05/26 21:34:58 drh Exp $
*/
#include "sqliteInt.h"
#include <stdarg.h>
#include <ctype.h>

/*
** If malloc() ever fails, this global variable gets set to 1.
................................................................................
** order is a little bit different.  See sqliteSortCompare below
** for additional information.
*/
int sqliteCompare(const char *atext, const char *btext){
  int result;
  int isNumA, isNumB;
  if( atext==0 ){
    return -1;
  }else if( btext==0 ){
    return 1;
  }
  isNumA = sqliteIsNumber(atext);
  isNumB = sqliteIsNumber(btext);
  if( isNumA ){
    if( !isNumB ){