B4BY.588

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Filename : subquery_bugs.result
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#
# Bug#27182010 SUBQUERY INCORRECTLY SHOWS DUPLICATE VALUES ON SUBQUERIES
#
CREATE TABLE p (Id INT,PRIMARY KEY (Id));
INSERT INTO p VALUES (1);
# Test UNIQUE KEY with NULL values
CREATE TABLE s (Id INT, u INT, UNIQUE KEY o(Id, u) );
INSERT INTO s VALUES (1, NULL),(1, NULL);
EXPLAIN SELECT p.Id FROM (p) WHERE p.Id IN (
SELECT s.Id FROM s WHERE Id=1 AND u IS NULL)ORDER BY Id DESC;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	p	system	PRIMARY	NULL	NULL	NULL	1	NULL
1	SIMPLE	s	ref	o	o	10	const,const	1	Using where; Using index; FirstMatch(p)
EXPLAIN SELECT p.Id FROM (p) WHERE p.Id IN (
SELECT s.Id FROM s WHERE Id=1 AND u IS NOT NULL) ORDER BY Id DESC;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	p	system	PRIMARY	NULL	NULL	NULL	1	NULL
1	SIMPLE	s	ref	o	o	5	const	1	Using where; Using index; FirstMatch(p)
SELECT p.Id FROM (p) WHERE p.Id IN (
SELECT s.Id FROM s WHERE Id=1 AND u IS NULL)ORDER BY Id DESC;
Id
1
SELECT p.Id FROM (p) WHERE p.Id IN (
SELECT s.Id FROM s WHERE Id=1 AND u IS NOT NULL) ORDER BY Id DESC;
Id
# UNIQUE KEY without NULL values
CREATE TABLE s1 (Id INT, u INT, UNIQUE KEY o(Id, u) );
INSERT INTO s1 VALUES (1, 2),(1, 3);
EXPLAIN SELECT p.Id FROM (p) WHERE p.Id IN (
SELECT s1.Id FROM s1 WHERE Id=1 AND u IS NOT NULL) ORDER BY Id DESC;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	p	system	PRIMARY	NULL	NULL	NULL	1	NULL
1	SIMPLE	s1	ref	o	o	5	const	1	Using where; Using index; FirstMatch(p)
EXPLAIN SELECT p.Id FROM (p) WHERE p.Id IN (
SELECT s1.Id FROM s1 WHERE Id=1 AND u != 1) ORDER BY Id DESC;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	p	system	PRIMARY	NULL	NULL	NULL	1	NULL
1	SIMPLE	s1	ref	o	o	5	const	1	Using where; Using index; FirstMatch(p)
SELECT p.Id FROM (p) WHERE p.Id IN (
SELECT s1.Id FROM s1 WHERE Id=1 AND u IS NOT NULL) ORDER BY Id DESC;
Id
1
SELECT p.Id FROM (p) WHERE p.Id IN (
SELECT s1.Id FROM s1 WHERE Id=1 AND u != 1) ORDER BY Id DESC;
Id
1
# NON UNIQUE KEY Scenario
CREATE TABLE s2 (Id INT, u INT, KEY o(Id, u) );
INSERT INTO s2 VALUES (1, NULL),(1, NULL);
#UNIQUE KEY with NON NULL FIELDS
CREATE TABLE s3 (Id INT NOT NULL, u INT NOT NULL, UNIQUE KEY o(Id, u));
INSERT INTO s3 VALUES (1, 2),(1, 3);
EXPLAIN SELECT p.Id FROM (p) WHERE p.Id IN (
SELECT s.Id FROM s2 s WHERE Id=1 AND u IS NULL) ORDER BY Id DESC;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	p	system	PRIMARY	NULL	NULL	NULL	1	NULL
1	SIMPLE	s	ref	o	o	10	const,const	1	Using where; Using index; FirstMatch(p)
EXPLAIN SELECT p.Id FROM (p) WHERE p.Id IN (
SELECT s.Id FROM s3 s WHERE Id=1 AND u IS NOT NULL)
ORDER BY Id DESC;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	p	system	PRIMARY	NULL	NULL	NULL	1	NULL
1	SIMPLE	s	ref	o	o	4	const	1	Using where; Using index; FirstMatch(p)
SELECT p.Id FROM (p) WHERE p.Id IN (
SELECT s.Id FROM s2 s WHERE Id=1 AND u IS NULL) ORDER BY Id DESC;
Id
1
SELECT p.Id FROM (p) WHERE p.Id IN (
SELECT s.Id FROM s3 s WHERE Id=1 AND u IS NOT NULL)
ORDER BY Id DESC;
Id
1
DROP TABLE p, s, s1, s2, s3;