来自多个表的值 [英] value from multiple tables

问题描述

大家好！

我有五个桌子:

Hi to all!

I have five tables:

umrf
mrf
mod
fun
rol

 fields of each tables are as

umrf={umrfid, uid, mrfid(FK)}

mrf = (mrfid(PK), modid(FK), rolid(FK), fnid(FK))

mod = {modid(PK), modname}

rolid = {rolid(PK), rolname}

mod = {modid(PK), fnname}

给定的是:

uid

并且我必须显示以下字段值:

mrfid，modname，rolname，fnname


这个怎么做?我已经尝试了很多次.

The given is:

uid

and I have to display field values of:

mrfid, modname, rolname, fnname


How to do this? I have try many times.

推荐答案

SELECT 
MR.MRFID,MO.Modname, RL.Rolname, FN.Fnname
FROM UMRF U 
INNER JOIN MRF MR ON U.MRFID=MR.MRFID
INNER JOIN MOD MO ON MR.MODID=MO.MODID
INNER JOIN FUN FN ON MR.FNID=FN.FNID
INNER JOIN ROL RL ON MR.ROLID=RL.ROLID
WHERE U.UID=...

使用一组

Use a set of inner joins[^] to get whatever values you require.

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