select * from teacher where s_id in(select s_id from student

来源：学生作业帮编辑：拍题作业网作业帮分类：综合作业时间：2024/04/30 21:25:02

select * from teacher where s_id in(select s_id from student) s_id栏位在student表中无,但是不报错
建立如下两个表
student(id,name)
teacher(id,name,s_id)
为什麽以下这个SQL不报错,S_ID栏位在student表中根本不存在
select * from teacher where s_id in(select s_id from student)?

当然不会报错,因为你的子查询只是借用了student这个表,而s_id是前边只是省略了前缀,全称是teacher.s_id,这样你就知道为什么不报错了吧?
你这个条件相当于就是恒成立的一个条件了.in里面的行数是根据student表的行数确定的.每一行都是这个s_id
再问：不是很明白，我是這樣理解的先執行IN裏面的子句，然後執行外面的，我的思路有問題？ select * from teacher where s_id in(select teacher.s_id from student)？ S_ID因為student表中沒所以被他當成是teacher表中的欄位了？

select * from teacher where s_id in(select s_id from student select id,name from student where id in ( select id from sco select * from order where clientNo in (select distinct(clien SELECT student_id FROM tuition where student_id in ( SELECT select * from user_info where user_name in (select user_name select * from student where name like '%[^ja,as,on]%' select ** from A where A.id in (select id from B where ****) SQL >select count(*) from Teacher where teacherCode=? and te 英语翻译select top 4 * from shop_books where anclassid = (select oracle 子查询:select *,(select account from t_ps_member m where ms sql :select * from (select *from b) as xxx where 和 select select * into b from a where 11