drop table if exists t1; select 1 in (1,2,3); 1 in (1,2,3) 1 select 10 in (1,2,3); 10 in (1,2,3) 0 select NULL in (1,2,3); NULL in (1,2,3) NULL select 1 in (1,NULL,3); 1 in (1,NULL,3) 1 select 3 in (1,NULL,3); 3 in (1,NULL,3) 1 select 10 in (1,NULL,3); 10 in (1,NULL,3) NULL select 1.5 in (1.5,2.5,3.5); 1.5 in (1.5,2.5,3.5) 1 select 10.5 in (1.5,2.5,3.5); 10.5 in (1.5,2.5,3.5) 0 select NULL in (1.5,2.5,3.5); NULL in (1.5,2.5,3.5) NULL select 1.5 in (1.5,NULL,3.5); 1.5 in (1.5,NULL,3.5) 1 select 3.5 in (1.5,NULL,3.5); 3.5 in (1.5,NULL,3.5) 1 select 10.5 in (1.5,NULL,3.5); 10.5 in (1.5,NULL,3.5) NULL CREATE TABLE t1 (a int, b int, c int); insert into t1 values (1,2,3), (1,NULL,3); select 1 in (a,b,c) from t1; 1 in (a,b,c) 1 1 select 3 in (a,b,c) from t1; 3 in (a,b,c) 1 1 select 10 in (a,b,c) from t1; 10 in (a,b,c) 0 NULL select NULL in (a,b,c) from t1; NULL in (a,b,c) NULL NULL drop table t1; CREATE TABLE t1 (a float, b float, c float); insert into t1 values (1.5,2.5,3.5), (1.5,NULL,3.5); select 1.5 in (a,b,c) from t1; 1.5 in (a,b,c) 1 1 select 3.5 in (a,b,c) from t1; 3.5 in (a,b,c) 1 1 select 10.5 in (a,b,c) from t1; 10.5 in (a,b,c) 0 NULL drop table t1; CREATE TABLE t1 (a varchar(10), b varchar(10), c varchar(10)); insert into t1 values ('A','BC','EFD'), ('A',NULL,'EFD'); select 'A' in (a,b,c) from t1; 'A' in (a,b,c) 1 1 select 'EFD' in (a,b,c) from t1; 'EFD' in (a,b,c) 1 1 select 'XSFGGHF' in (a,b,c) from t1; 'XSFGGHF' in (a,b,c) 0 NULL drop table t1; CREATE TABLE t1 (field char(1)); INSERT INTO t1 VALUES ('A'),(NULL); SELECT * from t1 WHERE field IN (NULL); field SELECT * from t1 WHERE field NOT IN (NULL); field SELECT * from t1 where field = field; field A SELECT * from t1 where field <=> field; field A NULL DELETE FROM t1 WHERE field NOT IN (NULL); SELECT * FROM t1; field A NULL drop table t1; create table t1 (id int(10) primary key); insert into t1 values (1),(2),(3),(4),(5),(6),(7),(8),(9); select * from t1 where id in (2,5,9); id 2 5 9 drop table t1; create table t1 ( a char(1) character set latin1 collate latin1_general_ci, b char(1) character set latin1 collate latin1_swedish_ci, c char(1) character set latin1 collate latin1_danish_ci ); insert into t1 values ('A','B','C'); insert into t1 values ('a','c','c'); select * from t1 where a in (b); ERROR HY000: Illegal mix of collations (latin1_general_ci,IMPLICIT) and (latin1_swedish_ci,IMPLICIT) for operation ' IN ' select * from t1 where a in (b,c); ERROR HY000: Illegal mix of collations (latin1_general_ci,IMPLICIT), (latin1_swedish_ci,IMPLICIT), (latin1_danish_ci,IMPLICIT) for operation ' IN ' select * from t1 where 'a' in (a,b,c); ERROR HY000: Illegal mix of collations for operation ' IN ' select * from t1 where 'a' in (a); a b c A B C a c c select * from t1 where a in ('a'); a b c A B C a c c select * from t1 where 'a' collate latin1_general_ci in (a,b,c); a b c A B C a c c select * from t1 where 'a' collate latin1_bin in (a,b,c); a b c a c c select * from t1 where 'a' in (a,b,c collate latin1_bin); a b c a c c explain extended select * from t1 where 'a' in (a,b,c collate latin1_bin); id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 ALL NULL NULL NULL NULL 2 Using where Warnings: Note 1003 select test.t1.a AS `a`,test.t1.b AS `b`,test.t1.c AS `c` from test.t1 where (_latin1'a' in (test.t1.a,test.t1.b,(test.t1.c collate _latin1'latin1_bin'))) drop table t1; set names utf8; create table t1 (a char(10) character set utf8 not null); insert into t1 values ('bbbb'),(_koi8r'����'),(_latin1'����'); select a from t1 where a in ('bbbb',_koi8r'����',_latin1'����') order by a; a ÄÄÄÄ bbbb цццц drop table t1; create table t1 (a char(10) character set latin1 not null); insert into t1 values ('a'),('b'),('c'); select a from t1 where a IN ('a','b','c') order by a; a a b c drop table t1; set names latin1; select '1.0' in (1,2); '1.0' in (1,2) 1 select 1 in ('1.0',2); 1 in ('1.0',2) 1 select 1 in (1,'2.0'); 1 in (1,'2.0') 1 select 1 in ('1.0',2.0); 1 in ('1.0',2.0) 1 select 1 in (1.0,'2.0'); 1 in (1.0,'2.0') 1 select 1 in ('1.1',2); 1 in ('1.1',2) 0 select 1 in ('1.1',2.0); 1 in ('1.1',2.0) 0 create table t1 (a char(20) character set binary); insert into t1 values ('aa'), ('bb'); select * from t1 where a in (NULL, 'aa'); a aa drop table t1; create table t1 (id int, key(id)); insert into t1 values (1),(2),(3); select count(*) from t1 where id not in (1); count(*) 2 select count(*) from t1 where id not in (1,2); count(*) 1 drop table t1;