drop table if exists t1;
create table t1 (id int auto_increment primary key not null, mydate date not null);
insert into t1 values (0,"2002-05-01"),(0,"2002-05-01"),(0,"2002-05-01");
flush tables;
select * from t1 where isnull(to_days(mydate));
id	mydate
drop table t1;
CREATE TABLE t1 (id INTEGER UNSIGNED NOT NULL AUTO_INCREMENT, PRIMARY KEY(id));
INSERT INTO t1( id ) VALUES ( NULL );
SELECT t1.id  FROM t1  WHERE (id  is not null and id is null );
id
DROP TABLE t1;