# # test of IN (NULL) # CREATE TABLE t1 (field char(1)); INSERT INTO t1 VALUES ('A'),(NULL); SELECT * from t1 WHERE field IN (NULL); SELECT * from t1 WHERE field NOT IN (NULL); SELECT * from t1 where field = field; SELECT * from t1 where field <=> field; DELETE FROM t1 WHERE field NOT IN (NULL); SELECT * FROM t1; 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); drop table t1;