关于在SQL中连接表 [英] Regarding joining tables in SQL

问题描述

我在加入两张桌子时遇到了麻烦。我想选择仅具有1998年特定年份的AID，价格和bname，属于欧米茄

I am having troubles joining two tables. I want to select AID, price and bname that have a specific year 1998 only and belong to omega

select AID, price, bname
from a, b
where ........

可以给出什么条件？

what condition can be given?

create table a
(AID number,
price number
year number,
pk (AID));
 
create table b
(BID number,
bname char,
pk(BID));
 
create table c
(AID number
BID number
pk(AID,BID)
fk (AID) references a(AID),
fk (BID) references b(BID));

insert into a values (1, 250, 1990);
insert into a values (2, 150, 1998);
insert into b values (1001, 'omega');
insert into b values (1002, 'sharp');
insert into c values (1, 1001);
insert into c values (2, 1002);

推荐答案

这与你之前的问题非常相似，但无论如何...



考虑以下

This is awfully similar to your previous question but anyhow...

Consider the following

select a.aid, a.price, b.bname
from a inner join c on a.AID = c.AID
       inner join b on c.BID = b.BID
where b.name = 'omega'
and   a.year = 1998;

我建议通过加入基础知识 [ ^ ]和类似的教程。

I would suggest going through Join Fundamentals[^] and similar tutorials.

尝试：

Try:

SELECT a.AID, a.Price, b.bName FROM a
JOIN c ON c.AID = a.AID
JOIN b ON c.BID = b.BID
WHERE b.bname = 'omega' AND a.year = 1998

但是...你的样本数据赢了;得到任何结果，因为没有这样的信息！

如果你改变了一年到1990年，或bname为sharp然后它将。

But...your sample data won;t give any results, because there is no such information!
If you change the year to 1990, or the bname to "sharp" then it will.

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