如何自兩端連接具有一定范圍值的表？

Question

有一個名為表teachers與教師的列的細節teacher_id ， role_code ， visit_tutor和class_code 。 如果role_code為'CT'並且visit_tutor為null則老師是該班的普通老師。 如果visit_tutor不為null則他是該班的客座老師。

如何獲得的名單teacher_id老師誰是類的普通教師與第class_code 'AA'和來訪班老師class_code 'BB' ？

以下代碼拋出錯誤，因為第一個子查詢返回多行：

select * from teachers where (
   select teacher_id from teachers t1 where t1.role_code='CT' and t1.class_code='AA'
) in (
   select teacher_id from teachers t2 where t2.visit_tutor is not null and t2.class_code='BB'
);

Answer 1

那不是怎么加入...

嘗試：

select t1.*
from teachers t1
inner join teachers t2
on t1.teacher_id = t2.teacher_id
where t1.role_code='CT' and t1.class_code='AA'
and t2.visit_tutor is not null and t2.class_code='BB'