加入2个表的查询 [英] Join Query on 2 tables

问题描述

Tables:
Book: BID,BNAME,BPRICE,SID
Author: AID,ANAME,BID

Question:
Write query which give list of Books, having more than one Author.

这个问题在采访中被问到了我。

This question was asked to me in interview.

推荐答案

如果你不知道，那么你不值得这份工作。



你能看到两个表都在列中的列吗？这是BID。所以sql是

If you didn't know, then you didn't deserve the job.

Can you see a column that both tables have in column ? It's BID. So the sql is

select b.bname, a.aname from book b inner join author a on b.bid = a.bid

获取所有列表作者和书籍。但是，你想要的是拥有多个作者的书籍。所以答案是：

to get a list of all authors and books. However, what you want, is books having more than one author. So the answer is:

select a.aname, count(b.bname) from book b inner join author a on b.bid = a.bid group by a.aname having count(b.bname) > 1

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