null_key.result
上传用户:romrleung
上传日期:2022-05-23
资源大小:18897k
文件大小:14k
- drop table if exists t1,t2;
- create 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 where; 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 where; 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 2 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
- create table t2 like t1;
- 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 3 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 3 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 3 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 1 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 12 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 5 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 4 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 3 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 3 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 1 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 4 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 1 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 1 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;
- rename table t2 to t1;
- 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 where; Using index
- select * from t1 where a = 7 and (b=7 or b is null);
- a b
- 7 7
- 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 range a,b a 10 NULL 3 Using where; Using index
- select * from t1 where (a = 7 or a is null) and (b=7 or b is null);
- a b
- NULL 7
- 7 NULL
- 7 7
- 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 5 Using where; Using index
- select * from t1 where (a = 7 or a is null) and (a = 7 or a is null);
- a b
- 7 NULL
- 7 7
- NULL 7
- NULL 9
- NULL 9
- 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 2
- 1 SIMPLE t1 ref a,b a 10 test.t2.a,const 2 Using where; Using index
- 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 2
- 1 SIMPLE t1 ref a a 10 test.t2.a,const 2 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 2
- 1 SIMPLE t1 ref_or_null a a 10 test.t2.a,const 4 Using where; Using index
- select * from t2,t1 where t1.a=t2.a and (b= 7 or b is null);
- a a b
- 7 7 7
- 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 2
- 1 SIMPLE t1 ref_or_null a a 10 test.t2.a,const 4 Using where; Using index
- select * from t2,t1 where (t1.a=t2.a or t1.a is null) and b= 7;
- a a b
- 7 7 7
- 7 NULL 7
- 8 8 7
- 8 NULL 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 2
- 1 SIMPLE t1 ref_or_null a a 5 test.t2.a 4 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
- 7 7 7
- 7 NULL 7
- 8 8 NULL
- 8 8 7
- 8 NULL 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 t2 ALL NULL NULL NULL NULL 4
- 1 SIMPLE t1 ref_or_null a a 5 test.t2.a 4 Using where; Using index
- 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 t2 ALL NULL NULL NULL NULL 4
- 1 SIMPLE t1 ref_or_null a a 5 test.t2.a 4 Using where; Using index
- select * from t2,t1 where t1.a<=>t2.a or (t1.a is null and t1.b <> 9);
- a a b
- 7 7 NULL
- 7 7 7
- 7 NULL 7
- 8 NULL 7
- NULL NULL 7
- NULL NULL 9
- NULL NULL 9
- 6 6 6
- 6 NULL 7
- drop table t1,t2;
- CREATE TABLE t1 (
- id int(10) unsigned NOT NULL auto_increment,
- uniq_id int(10) unsigned default NULL,
- PRIMARY KEY (id),
- UNIQUE KEY idx1 (uniq_id)
- ) ENGINE=MyISAM;
- CREATE TABLE t2 (
- id int(10) unsigned NOT NULL auto_increment,
- uniq_id int(10) unsigned 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 1 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 TABLE `t1` (
- `order_id` char(32) NOT NULL default '',
- `product_id` char(32) NOT NULL default '',
- `product_type` int(11) NOT NULL default '0',
- PRIMARY KEY (`order_id`,`product_id`,`product_type`)
- ) ENGINE=MyISAM;
- CREATE TABLE `t2` (
- `order_id` char(32) NOT NULL default '',
- `product_id` char(32) NOT NULL default '',
- `product_type` int(11) 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);
- Warnings:
- Warning 1263 Data truncated; NULL supplied to NOT NULL column 'id2' at row 1
- select * from t1;
- id id2
- NULL 0
- 1 1
- select * from t1 where id <=> null;
- id id2
- NULL 0
- select * from t1 where id <=> null or id > 0;
- id id2
- NULL 0
- 1 1
- select * from t1 where id is null or id > 0;
- id id2
- NULL 0
- 1 1
- select * from t1 where id2 <=> null or id2 > 0;
- id id2
- 1 1
- select * from t1 where id2 is null or id2 > 0;
- id id2
- 1 1
- delete from t1 where id <=> NULL;
- select * from t1;
- id id2
- 1 1
- 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 4
- 1 SIMPLE t2 ref idx idx 5 test.t1.a 1
- 1 SIMPLE t3 ref idx idx 5 test.t2.b 1 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 0
- Handler_read_key 6
- Handler_read_next 2
- Handler_read_prev 0
- Handler_read_rnd 0
- Handler_read_rnd_next 5
- DROP TABLE t1,t2,t3,t4;