子查询
θsome与 θall子查询
=some和in的关系同
表达式 = some（子查询）
表达式 in （子查询）
select
Sname
from
Student S
where
S#
in(select S# from SC where S# = S.S# and C#='001');
select
Sname
from
Student S
where
S# =some (select S# from SC where S# = S.S# and C#='001');
<>all和not in的关系同
select
Sname
from
Student S
where
S# not in(select S# from SC where S# = S.S# and C#='001');
select
Sname
from
Student S
where
S# <>al
版权声明：本文为zmjheart原创文章，遵循 CC 4.0 BY-SA 版权协议，转载请附上原文出处链接和本声明。