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drop table if exists t1,t2;
create temporary table t1 (a int, b int not null,unique key (a,b),index(b)) engine=myisam;
insert ignore into t1 values (1,1),(2,2),(3,3),(4,4),(5,5),(6,6),(null,7),(9,9),(8,8),(7,7),(null,9),(null,9),(6,6);
explain select * from t1 where a is null;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref a a 5 const 3 Using where; Using index
explain select * from t1 where a is null and b = 2;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref a,b a 9 const,const 1 Using where; Using index
explain select * from t1 where a is null and b = 7;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref a,b a 9 const,const 1 Using where; Using index
explain select * from t1 where a=2 and b = 2;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 const a,b a 9 const,const 1 Using index
explain select * from t1 where a<=>b limit 2;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 index NULL a 9 NULL 12 Using where; Using index
explain select * from t1 where (a is null or a > 0 and a < 3) and b < 5 limit 3;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range a,b a 9 NULL 3 Using where; Using index
explain select * from t1 where (a is null or a = 7) and b=7;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref_or_null a,b a 9 const,const 2 Using index
explain select * from t1 where (a is null or a = 7) and b=7 order by a;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref_or_null a,b a 9 const,const 2 Using index; Using filesort
explain select * from t1 where (a is null and b>a) or a is null and b=7 limit 2;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref a,b a 5 const 3 Using where; Using index
explain select * from t1 where a is null and b=9 or a is null and b=7 limit 3;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range a,b a 9 NULL 3 Using where; Using index
explain select * from t1 where a > 1 and a < 3 limit 1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range a a 5 NULL 1 Using where; Using index
explain select * from t1 where a > 8 and a < 9;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range a a 5 NULL 1 Using where; Using index
select * from t1 where a is null;
a b
NULL 7
NULL 9
NULL 9
select * from t1 where a is null and b = 7;
a b
NULL 7
select * from t1 where a<=>b limit 2;
a b
1 1
2 2
select * from t1 where (a is null or a > 0 and a < 3) and b < 5 limit 3;
a b
1 1
2 2
select * from t1 where (a is null or a > 0 and a < 3) and b > 7 limit 3;
a b
NULL 9
NULL 9
select * from t1 where (a is null or a = 7) and b=7;
a b
7 7
NULL 7
select * from t1 where a is null and b=9 or a is null and b=7 limit 3;
a b
NULL 7
NULL 9
NULL 9
select * from t1 where a > 1 and a < 3 limit 1;
a b
2 2
select * from t1 where a > 8 and a < 9;
a b
create table t2 like t1;
ERROR HY000: Can't create table 'test.t2' (errno: 138)
create temporary table t2 like t1;
show create table t2;
Table Create Table
t2 CREATE TEMPORARY TABLE `t2` (
`a` int DEFAULT NULL,
`b` int NOT NULL,
UNIQUE KEY `a` (`a`,`b`),
KEY `b` (`b`)
) ENGINE=MyISAM
insert into t2 select * from t1;
alter table t1 modify b blob not null, add c int not null, drop key a, add unique key (a,b(20),c), drop key b, add key (b(10));
explain select * from t1 where a is null and b = 2;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref a,b a 5 const X Using where
explain select * from t1 where a is null and b = 2 and c=0;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref a,b a 5 const X Using where
explain select * from t1 where a is null and b = 7 and c=0;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref a,b a 5 const X Using where
explain select * from t1 where a=2 and b = 2;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref a,b a 5 const X Using where
explain select * from t1 where a<=>b limit 2;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL X Using where
explain select * from t1 where (a is null or a > 0 and a < 3) and b < 5 and c=0 limit 3;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range a,b a 5 NULL X Using where
explain select * from t1 where (a is null or a = 7) and b=7 and c=0;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref_or_null a,b a 5 const X Using where
explain select * from t1 where (a is null and b>a) or a is null and b=7 limit 2;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref a,b a 5 const X Using where
explain select * from t1 where a is null and b=9 or a is null and b=7 limit 3;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref a,b a 5 const X Using where
explain select * from t1 where a > 1 and a < 3 limit 1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range a a 5 NULL X Using where
explain select * from t1 where a is null and b=7 or a > 1 and a < 3 limit 1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range a,b a 5 NULL X Using where
explain select * from t1 where a > 8 and a < 9;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range a a 5 NULL X Using where
explain select * from t1 where b like "6%";
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range b b 12 NULL X Using where
select * from t1 where a is null;
a b c
NULL 7 0
NULL 9 0
NULL 9 0
select * from t1 where a is null and b = 7 and c=0;
a b c
NULL 7 0
select * from t1 where a<=>b limit 2;
a b c
1 1 0
2 2 0
select * from t1 where (a is null or a > 0 and a < 3) and b < 5 limit 3;
a b c
1 1 0
2 2 0
select * from t1 where (a is null or a > 0 and a < 3) and b > 7 limit 3;
a b c
NULL 9 0
NULL 9 0
select * from t1 where (a is null or a = 7) and b=7 and c=0;
a b c
7 7 0
NULL 7 0
select * from t1 where a is null and b=9 or a is null and b=7 limit 3;
a b c
NULL 7 0
NULL 9 0
NULL 9 0
select * from t1 where b like "6%";
a b c
6 6 0
drop table t1;
drop table t2;
create temporary table t1 (a int, b int not null,unique key (a,b),index(b)) engine=myisam;
alter table t1 modify b int null;
insert into t1 values (7,null), (8,null), (8,7);
explain select * from t1 where a = 7 and (b=7 or b is null);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref_or_null a,b a 10 const,const 2 Using index
select * from t1 where a = 7 and (b=7 or b is null);
a b
7 NULL
explain select * from t1 where (a = 7 or a is null) and (b=7 or b is null);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref_or_null a,b a 5 const 2 Using where; Using index
select * from t1 where (a = 7 or a is null) and (b=7 or b is null);
a b
7 NULL
explain select * from t1 where (a = 7 or a is null) and (a = 7 or a is null);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref_or_null a a 5 const 2 Using index
select * from t1 where (a = 7 or a is null) and (a = 7 or a is null);
a b
7 NULL
create table t2 (a int);
insert into t2 values (7),(8);
explain select * from t2 straight_join t1 where t1.a=t2.a and b is null;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 ALL NULL NULL NULL NULL X
1 SIMPLE t1 ref a,b b 5 const X Using where
drop index b on t1;
explain select * from t2,t1 where t1.a=t2.a and b is null;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 ALL NULL NULL NULL NULL X
1 SIMPLE t1 ref a a 10 test.t2.a,const X Using where; Using index
select * from t2,t1 where t1.a=t2.a and b is null;
a a b
7 7 NULL
8 8 NULL
explain select * from t2,t1 where t1.a=t2.a and (b= 7 or b is null);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 ALL NULL NULL NULL NULL X
1 SIMPLE t1 ref_or_null a a 10 test.t2.a,const X Using index
select * from t2,t1 where t1.a=t2.a and (b= 7 or b is null);
a a b
7 7 NULL
8 8 7
8 8 NULL
explain select * from t2,t1 where (t1.a=t2.a or t1.a is null) and b= 7;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 ALL NULL NULL NULL NULL X
1 SIMPLE t1 ref_or_null a a 10 test.t2.a,const X Using index
select * from t2,t1 where (t1.a=t2.a or t1.a is null) and b= 7;
a a b
8 8 7
explain select * from t2,t1 where (t1.a=t2.a or t1.a is null) and (b= 7 or b is null);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 ALL NULL NULL NULL NULL X
1 SIMPLE t1 ref_or_null a a 5 test.t2.a X Using where; Using index
select * from t2,t1 where (t1.a=t2.a or t1.a is null) and (b= 7 or b is null);
a a b
7 7 NULL
8 8 NULL
8 8 7
insert into t2 values (null),(6);
delete from t1 where a=8;
explain select * from t2,t1 where t1.a=t2.a or t1.a is null;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 system a NULL NULL NULL X
1 SIMPLE t2 ALL NULL NULL NULL NULL X Using where
explain select * from t2,t1 where t1.a<=>t2.a or (t1.a is null and t1.b <> 9);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 system a NULL NULL NULL X
1 SIMPLE t2 ALL NULL NULL NULL NULL X Using where
select * from t2,t1 where t1.a<=>t2.a or (t1.a is null and t1.b <> 9);
a a b
7 7 NULL
drop table t1,t2;
CREATE TEMPORARY TABLE t1 (
id int NOT NULL auto_increment,
uniq_id int default NULL,
PRIMARY KEY (id),
UNIQUE KEY idx1 (uniq_id)
) ENGINE=MyISAM;
CREATE TEMPORARY TABLE t2 (
id int NOT NULL auto_increment,
uniq_id int default NULL,
PRIMARY KEY (id)
) ENGINE=MyISAM;
INSERT INTO t1 VALUES (1,NULL),(2,NULL),(3,1),(4,2),(5,NULL),(6,NULL),(7,3),(8,4),(9,NULL),(10,NULL);
INSERT INTO t2 VALUES (1,NULL),(2,NULL),(3,1),(4,2),(5,NULL),(6,NULL),(7,3),(8,4),(9,NULL),(10,NULL);
explain select id from t1 where uniq_id is null;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref idx1 idx1 5 const 5 Using where
explain select id from t1 where uniq_id =1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 const idx1 idx1 5 const 1
UPDATE t1 SET id=id+100 where uniq_id is null;
UPDATE t2 SET id=id+100 where uniq_id is null;
select id from t1 where uniq_id is null;
id
101
102
105
106
109
110
select id from t2 where uniq_id is null;
id
101
102
105
106
109
110
DELETE FROM t1 WHERE uniq_id IS NULL;
DELETE FROM t2 WHERE uniq_id IS NULL;
SELECT * FROM t1 ORDER BY uniq_id, id;
id uniq_id
3 1
4 2
7 3
8 4
SELECT * FROM t2 ORDER BY uniq_id, id;
id uniq_id
3 1
4 2
7 3
8 4
DROP table t1,t2;
CREATE TEMPORARY TABLE `t1` (
`order_id` char(32) NOT NULL default '',
`product_id` char(32) NOT NULL default '',
`product_type` int NOT NULL default '0',
PRIMARY KEY (`order_id`,`product_id`,`product_type`)
) ENGINE=MyISAM;
CREATE TEMPORARY TABLE `t2` (
`order_id` char(32) NOT NULL default '',
`product_id` char(32) NOT NULL default '',
`product_type` int NOT NULL default '0',
PRIMARY KEY (`order_id`,`product_id`,`product_type`)
) ENGINE=MyISAM;
INSERT INTO t1 (order_id, product_id, product_type) VALUES
('3d7ce39b5d4b3e3d22aaafe9b633de51',1206029, 3),
('3d7ce39b5d4b3e3d22aaafe9b633de51',5880836, 3),
('9d9aad7764b5b2c53004348ef8d34500',2315652, 3);
INSERT INTO t2 (order_id, product_id, product_type) VALUES
('9d9aad7764b5b2c53004348ef8d34500',2315652, 3);
select t1.* from t1
left join t2 using(order_id, product_id, product_type)
where t2.order_id=NULL;
order_id product_id product_type
select t1.* from t1
left join t2 using(order_id, product_id, product_type)
where t2.order_id is NULL;
order_id product_id product_type
3d7ce39b5d4b3e3d22aaafe9b633de51 1206029 3
3d7ce39b5d4b3e3d22aaafe9b633de51 5880836 3
drop table t1,t2;
create table t1 (id int);
insert into t1 values (null), (0);
create table t2 (id int);
insert into t2 values (null);
select * from t1, t2 where t1.id = t2.id;
id id
alter table t1 add key id (id);
select * from t1, t2 where t1.id = t2.id;
id id
drop table t1,t2;
create table t1 (
id integer,
id2 integer not null,
index (id),
index (id2)
);
insert into t1 values(null,null),(1,1);
ERROR 23000: Column 'id2' cannot be null
select * from t1;
id id2
select * from t1 where id <=> null;
id id2
select * from t1 where id <=> null or id > 0;
id id2
select * from t1 where id is null or id > 0;
id id2
select * from t1 where id2 <=> null or id2 > 0;
id id2
select * from t1 where id2 is null or id2 > 0;
id id2
delete from t1 where id <=> NULL;
select * from t1;
id id2
drop table t1;
CREATE TABLE t1 (a int);
CREATE TABLE t2 (a int, b int, INDEX idx(a));
CREATE TABLE t3 (b int, INDEX idx(b));
CREATE TABLE t4 (b int, INDEX idx(b));
INSERT INTO t1 VALUES (1), (2), (3), (4);
INSERT INTO t2 VALUES (1, 1), (3, 1);
INSERT INTO t3 VALUES
(NULL), (NULL), (NULL), (NULL), (NULL),
(NULL), (NULL), (NULL), (NULL), (NULL);
INSERT INTO t4 SELECT * FROM t3;
INSERT INTO t3 SELECT * FROM t4;
INSERT INTO t4 SELECT * FROM t3;
INSERT INTO t3 SELECT * FROM t4;
INSERT INTO t4 SELECT * FROM t3;
INSERT INTO t3 SELECT * FROM t4;
INSERT INTO t4 SELECT * FROM t3;
INSERT INTO t3 SELECT * FROM t4;
INSERT INTO t4 SELECT * FROM t3;
INSERT INTO t3 SELECT * FROM t4;
INSERT INTO t4 SELECT * FROM t3;
INSERT INTO t3 SELECT * FROM t4;
INSERT INTO t4 SELECT * FROM t3;
INSERT INTO t3 SELECT * FROM t4;
INSERT INTO t4 SELECT * FROM t3;
INSERT INTO t3 SELECT * FROM t4;
INSERT INTO t3 VALUES (2), (3);
ANALYZE table t1, t2, t3;
Table Op Msg_type Msg_text
test.t1 analyze status OK
test.t2 analyze status OK
test.t3 analyze status OK
SELECT COUNT(*) FROM t3;
COUNT(*)
15972
EXPLAIN SELECT SQL_CALC_FOUND_ROWS * FROM t1 LEFT JOIN t2 ON t1.a=t2.a
LEFT JOIN t3 ON t2.b=t3.b;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL X
1 SIMPLE t2 ref idx idx 5 test.t1.a X
1 SIMPLE t3 ref idx idx 5 test.t2.b X Using index
FLUSH STATUS ;
SELECT SQL_CALC_FOUND_ROWS * FROM t1 LEFT JOIN t2 ON t1.a=t2.a
LEFT JOIN t3 ON t2.b=t3.b;
a a b b
1 1 1 NULL
2 NULL NULL NULL
3 3 1 NULL
4 NULL NULL NULL
SELECT FOUND_ROWS();
FOUND_ROWS()
4
SHOW STATUS LIKE "handler_read%";
Variable_name Value
Handler_read_first 1
Handler_read_key 10
Handler_read_next 2
Handler_read_prev 0
Handler_read_rnd 0
Handler_read_rnd_next 5
DROP TABLE t1,t2,t3,t4;
CREATE TABLE t1 (
a int default NULL,
b int default NULL,
KEY a (a,b)
);
INSERT INTO t1 VALUES (0,10),(0,11),(0,12);
CREATE TABLE t2 (
a int default NULL,
b int default NULL,
KEY a (a)
);
INSERT INTO t2 VALUES (3,NULL),(3,11),(3,12);
SELECT * FROM t2 inner join t1 WHERE ( t1.a = 0 OR t1.a IS NULL) AND t2.a = 3 AND t2.b = t1.b;
a b a b
3 11 0 11
3 12 0 12
drop table t1, t2;
End of 5.0 tests
|