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); Warnings: Warning 1062 Duplicate entry '6-6' for key 'a' 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 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; 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 ref_or_null a,b a 5 const 4 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 7 7 NULL 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 Using where 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 Using where 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 Using where 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 5 Using index condition 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 1048 Column 'id2' cannot be null 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 Using where 1 SIMPLE t3 ref idx idx 5 test.t2.b 1 Using where; 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_last 0 Handler_read_next 2 Handler_read_prev 0 Handler_read_retry 0 Handler_read_rnd 0 Handler_read_rnd_deleted 0 Handler_read_rnd_next 5 DROP TABLE t1,t2,t3,t4; CREATE TABLE t1 ( a int(11) default NULL, b int(11) default NULL, KEY a (a,b) ); INSERT INTO t1 VALUES (0,10),(0,11),(0,12); CREATE TABLE t2 ( a int(11) default NULL, b int(11) 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 # # BUG#727667 Wrong result with OR + NOT NULL in maria-5.3 # CREATE TABLE t1 ( f3 int(11), f10 varchar(1), KEY (f3) ); INSERT INTO t1 VALUES ('9','k'),(NULL,'r'); SELECT * FROM t1 WHERE (f3 = 83) OR (f10 = 'z' AND f3 IS NULL); f3 f10 DROP TABLE t1;