select * from teacher where s_id in(select s_id from student
来源:学生作业帮 编辑:神马作文网作业帮 分类:综合作业 时间:2024/09/20 18:38:33
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)?
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?
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