drop table if exists t1;
select {fn length("hello")}, { date "1997-10-20" };
{fn length("hello")}	1997-10-20
5	1997-10-20
create table t1 (a int not null auto_increment,b int not null,primary key (a,b));
insert into t1 SET A=NULL,B=1;
insert into t1 SET a=null,b=2;
select * from t1 where a is null and b=2;
a	b
2	2
select * from t1 where a is null;
a	b
explain select * from t1 where b is null;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Impossible WHERE
drop table t1;
CREATE TABLE t1 (a INT AUTO_INCREMENT PRIMARY KEY);
INSERT INTO t1 VALUES (NULL);
SELECT sql_no_cache a, last_insert_id() FROM t1 WHERE a IS NULL;
a	last_insert_id()
1	1
SELECT sql_no_cache a, last_insert_id() FROM t1 WHERE a IS NULL;
a	last_insert_id()
SELECT sql_no_cache a, last_insert_id() FROM t1;
a	last_insert_id()
1	1
DROP TABLE t1;