create table tb(id int , del int) insert into tb(del) select 0 insert into tb(del) select 1 insert into tb(id ,del) select 2,2 insert into tb(id ,del) select 4,1 select * from tb where id is null and del = 0/* id del --------------- NULL 0 */drop table tb
insert into tb(del) select 0
insert into tb(del) select 1
insert into tb(id ,del) select 2,2
insert into tb(id ,del) select 4,1
select * from tb where id is null and del = 0/*
id del
---------------
NULL 0
*/drop table tb