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Overview
Comment:Fix a problem with NULL handling in aggregate min/max when returning values from the row containing the min or max.
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SHA1:f27c7b4fb193126548e6a620ac89664d1efa3856
User & Date: drh 2012-02-02 18:42:09
Context
2012-02-02
18:46
When non-aggregate columns occur in an aggregate query with a single min() or max(), then the values of the non-aggregate columns are taken from one of the rows that was the min() or max(). check-in: fa13edd3 user: drh tags: trunk
18:42
Fix a problem with NULL handling in aggregate min/max when returning values from the row containing the min or max. Closed-Leaf check-in: f27c7b4f user: drh tags: output-minmax-row
17:35
For queries of the form "SELECT p, max(q) FROM t1", the value of column p returned is the one on the same row that holds the maximum value of q. check-in: adb29232 user: drh tags: output-minmax-row
Changes
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Changes to src/func.c.

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  int NotUsed, 
  sqlite3_value **argv
){
  Mem *pArg  = (Mem *)argv[0];
  Mem *pBest;
  UNUSED_PARAMETER(NotUsed);

  if( sqlite3_value_type(argv[0])==SQLITE_NULL ) return;
  pBest = (Mem *)sqlite3_aggregate_context(context, sizeof(*pBest));
  if( !pBest ) return;



  if( pBest->flags ){
    int max;
    int cmp;
    CollSeq *pColl = sqlite3GetFuncCollSeq(context);
    /* This step function is used for both the min() and max() aggregates,
    ** the only difference between the two being that the sense of the
    ** comparison is inverted. For the max() aggregate, the
    ** sqlite3_user_data() function returns (void *)-1. For min() it
................................................................................
    sqlite3VdbeMemCopy(pBest, pArg);
  }
}
static void minMaxFinalize(sqlite3_context *context){
  sqlite3_value *pRes;
  pRes = (sqlite3_value *)sqlite3_aggregate_context(context, 0);
  if( pRes ){
    if( ALWAYS(pRes->flags) ){
      sqlite3_result_value(context, pRes);
    }
    sqlite3VdbeMemRelease(pRes);
  }
}

/*







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  int NotUsed, 
  sqlite3_value **argv
){
  Mem *pArg  = (Mem *)argv[0];
  Mem *pBest;
  UNUSED_PARAMETER(NotUsed);


  pBest = (Mem *)sqlite3_aggregate_context(context, sizeof(*pBest));
  if( !pBest ) return;

  if( sqlite3_value_type(argv[0])==SQLITE_NULL ){
    if( pBest->flags ) sqlite3SkipAccumulatorLoad(context);
  }else if( pBest->flags ){
    int max;
    int cmp;
    CollSeq *pColl = sqlite3GetFuncCollSeq(context);
    /* This step function is used for both the min() and max() aggregates,
    ** the only difference between the two being that the sense of the
    ** comparison is inverted. For the max() aggregate, the
    ** sqlite3_user_data() function returns (void *)-1. For min() it
................................................................................
    sqlite3VdbeMemCopy(pBest, pArg);
  }
}
static void minMaxFinalize(sqlite3_context *context){
  sqlite3_value *pRes;
  pRes = (sqlite3_value *)sqlite3_aggregate_context(context, 0);
  if( pRes ){
    if( pRes->flags ){
      sqlite3_result_value(context, pRes);
    }
    sqlite3VdbeMemRelease(pRes);
  }
}

/*

Changes to test/e_select.test.

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  2  "SELECT * FROM z1,z2 LIMIT 1"          {51.65 -59.58 belfries {} 21}
  3  "SELECT z1.* FROM z1,z2 LIMIT 1"       {51.65 -59.58 belfries}
  4  "SELECT z2.* FROM z1,z2 LIMIT 1"       {{} 21}
  5  "SELECT z2.*, z1.* FROM z1,z2 LIMIT 1" {{} 21 51.65 -59.58 belfries}

  6  "SELECT count(*), * FROM z1"           {6 63 born -26}
  7  "SELECT max(a), * FROM z1"             {63 63 born -26}
  8  "SELECT *, min(a) FROM z1"             {{} 67 quartets -5}

  9  "SELECT *,* FROM z1,z2 LIMIT 1" {        
     51.65 -59.58 belfries {} 21 51.65 -59.58 belfries {} 21
  }
  10 "SELECT z1.*,z1.* FROM z2,z1 LIMIT 1" {        
     51.65 -59.58 belfries 51.65 -59.58 belfries
  }







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  2  "SELECT * FROM z1,z2 LIMIT 1"          {51.65 -59.58 belfries {} 21}
  3  "SELECT z1.* FROM z1,z2 LIMIT 1"       {51.65 -59.58 belfries}
  4  "SELECT z2.* FROM z1,z2 LIMIT 1"       {{} 21}
  5  "SELECT z2.*, z1.* FROM z1,z2 LIMIT 1" {{} 21 51.65 -59.58 belfries}

  6  "SELECT count(*), * FROM z1"           {6 63 born -26}
  7  "SELECT max(a), * FROM z1"             {63 63 born -26}
  8  "SELECT *, min(a) FROM z1"             {-5 {} 75 -5}

  9  "SELECT *,* FROM z1,z2 LIMIT 1" {        
     51.65 -59.58 belfries {} 21 51.65 -59.58 belfries {} 21
  }
  10 "SELECT z1.*,z1.* FROM z2,z1 LIMIT 1" {        
     51.65 -59.58 belfries 51.65 -59.58 belfries
  }

Added test/minmax4.test.



































































































































































































































































































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# 2012 February 02
#
# The author disclaims copyright to this source code.  In place of
# a legal notice, here is a blessing:
#
#    May you do good and not evil.
#    May you find forgiveness for yourself and forgive others.
#    May you share freely, never taking more than you give.
#
#***********************************************************************
#
# Test for queries of the form:  
#
#    SELECT p, max(q) FROM t1;
#
# Demonstration that the value returned for p is on the same row as 
# the maximum q.
#

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

do_test minmax4-1.1 {
  db eval {
    CREATE TABLE t1(p,q);
    SELECT p, max(q) FROM t1;
  }
} {{} {}}
do_test minmax4-1.2 {
  db eval {
    SELECT p, min(q) FROM t1;
  }
} {{} {}}
do_test minmax4-1.3 {
  db eval {
    INSERT INTO t1 VALUES(1,2);
    SELECT p, max(q) FROM t1;
  }
} {1 2}
do_test minmax4-1.4 {
  db eval {
    SELECT p, min(q) FROM t1;
  }
} {1 2}
do_test minmax4-1.5 {
  db eval {
    INSERT INTO t1 VALUES(3,4);
    SELECT p, max(q) FROM t1;
  }
} {3 4}
do_test minmax4-1.6 {
  db eval {
    SELECT p, min(q) FROM t1;
  }
} {1 2}
do_test minmax4-1.7 {
  db eval {
    INSERT INTO t1 VALUES(5,0);
    SELECT p, max(q) FROM t1;
  }
} {3 4}
do_test minmax4-1.8 {
  db eval {
    SELECT p, min(q) FROM t1;
  }
} {5 0}
do_test minmax4-1.9 {
  db eval {
    INSERT INTO t1 VALUES(6,1);
    SELECT p, max(q) FROM t1;
  }
} {3 4}
do_test minmax4-1.10 {
  db eval {
    SELECT p, min(q) FROM t1;
  }
} {5 0}
do_test minmax4-1.11 {
  db eval {
    INSERT INTO t1 VALUES(7,NULL);
    SELECT p, max(q) FROM t1;
  }
} {3 4}
do_test minmax4-1.12 {
  db eval {
    SELECT p, min(q) FROM t1;
  }
} {5 0}
do_test minmax4-1.13 {
  db eval {
    DELETE FROM t1 WHERE q IS NOT NULL;
    SELECT p, max(q) FROM t1;
  }
} {7 {}}
do_test minmax4-1.14 {
  db eval {
    SELECT p, min(q) FROM t1;
  }
} {7 {}}

do_test minmax4-2.1 {
  db eval {
    CREATE TABLE t2(a,b,c);
    INSERT INTO t2 VALUES
         (1,null,2),
         (1,2,3),
         (1,1,4),
         (2,3,5);
    SELECT a, max(b), c FROM t2 GROUP BY a ORDER BY a;
  }
} {1 2 3 2 3 5}
do_test minmax4-2.2 {
  db eval {
    SELECT a, min(b), c FROM t2 GROUP BY a ORDER BY a;
  }
} {1 1 4 2 3 5}
do_test minmax4-2.3 {
  db eval {
    SELECT a, min(b), avg(b), count(b), c FROM t2 GROUP BY a ORDER BY a DESC;
  }
} {2 3 3.0 1 5 1 1 1.5 2 4}
do_test minmax4-2.4 {
  db eval {
    SELECT a, min(b), max(b), c FROM t2 GROUP BY a ORDER BY a;
  }
} {1 1 2 3 2 3 3 5}
do_test minmax4-2.5 {
  db eval {
    SELECT a, max(b), min(b), c FROM t2 GROUP BY a ORDER BY a;
  }
} {1 2 1 4 2 3 3 5}
do_test minmax4-2.6 {
  db eval {
    SELECT a, max(b), b, max(c), c FROM t2 GROUP BY a ORDER BY a;
  }
} {1 2 1 4 4 2 3 3 5 5}
do_test minmax4-2.7 {
  db eval {
    SELECT a, min(b), b, min(c), c FROM t2 GROUP BY a ORDER BY a;
  }
} {1 1 {} 2 2 2 3 3 5 5}



finish_test