# BUG#48920: COUNT DISTINCT returns 1 for NULL values when in a subquery
# in the select list
#
CREATE TABLE t1 (
i int(11) DEFAULT NULL,
v varchar(1) DEFAULT NULL
);
INSERT INTO t1 VALUES (8,'v');
INSERT INTO t1 VALUES (9,'r');
INSERT INTO t1 VALUES (NULL,'y');
CREATE TABLE t2 (
i int(11) DEFAULT NULL,
v varchar(1) DEFAULT NULL,
KEY i_key (i)
);
INSERT INTO t2 VALUES (NULL,'r');
INSERT INTO t2 VALUES (0,'c');
INSERT INTO t2 VALUES (0,'o');
INSERT INTO t2 VALUES (2,'v');
INSERT INTO t2 VALUES (7,'c');
SELECT i, v, (SELECT COUNT(DISTINCT i)
FROM t1
WHERE v = t2.v) as subsel
FROM t2;
i v subsel
NULL r 1
0 c 0
0 o 0
2 v 1
7 c 0
EXPLAIN EXTENDED
SELECT i, v, (SELECT COUNT(DISTINCT i)
FROM t1
WHERE v = t2.v) as subsel
FROM t2;
id select_type table type possible_keys key key_len ref rows filtered Extra
1 PRIMARY t2 ALL NULL NULL NULL NULL 5 100.00
2 DEPENDENT SUBQUERY t1 ALL NULL NULL NULL NULL 3 100.00 Using where
Warnings:
Note 1276 Field or reference 'test.t2.v' of SELECT #2 was resolved in SELECT #1
Note 1003 select `test`.`t2`.`i` AS `i`,`test`.`t2`.`v` AS `v`,(select count(distinct `test`.`t1`.`i`) AS `COUNT(DISTINCT i)` from `test`.`t1` where (`test`.`t1`.`v` = `test`.`t2`.`v`)) AS `subsel` from `test`.`t2`
@@ -51,8 +51,8 @@ CREATE TABLE t3 (pk1 int unsigned NOT NULL PRIMARY KEY, attr1 int unsigned NO
insert into t3 values (0,0,0,0,"a"),(1,1,9223372036854775803,1,"b"),(2,2,9223372036854775804,2,"c"),(3,3,9223372036854775805,3,"d"),(4,4,9223372036854775806,4,"e"),(5,5,9223372036854775807,5,"f");
CREATE TABLE t4 (pk1 int unsigned NOT NULL PRIMARY KEY, attr1 int unsigned NOT NULL, attr2 bigint unsigned, attr3 tinyint unsigned, attr4 VARCHAR(10) , KEY (attr1)) ENGINE=ndbcluster;
insert into t4 values (0,0,0,0,"a"),(1,1,9223372036854775803,1,"b"),(2,2,9223372036854775804,2,"c"),(3,3,9223372036854775805,3,"d"),(4,4,9223372036854775806,4,"e"),(5,5,9223372036854775807,5,"f");
set @old_ecpd = @@session.engine_condition_pushdown;
set engine_condition_pushdown = off;
set @old_optimizer_switch = @@session.optimizer_switch;
set optimizer_switch = "engine_condition_pushdown=off";