MySQL从表中选择一个字段，条件在多行中 [英] MySQL select one field from table WHERE condition is in multiple rows

问题描述

试图找到答案，但仍然找不到..下表如下:

Tried to find the answer, but still couldn't.. The table is as follows:

id, keyword,   value
1   display    15.6
1   harddrive  320
1   ram        3

所以我需要的是这样的.从此表中选择一个ID，其中(keyword="display" and value="15.6") AND (keyword="harddrive" and value="320") 可能还会有3或4个这样的关键字条件，导致返回一个ID(一行)

So what i need is something like this.. Select an id from this table where (keyword="display" and value="15.6") AND (keyword="harddrive" and value="320") There's also a possibility that there will be 3 or 4 such keyword conditions which should result into returning one id (one row)

似乎有一些可以处理UNION的东西，但是我以前没有使用过它，所以我无法弄清楚

It seems there's something to deal with UNION but i didn't use it before so i can't figure it out

预先感谢

推荐答案

这是

This is a relational division problem. Something like the following should do it.

SELECT id
FROM your_table
WHERE 
(keyword="display" and value="15.6") OR (keyword="harddrive" and value="320")
GROUP BY id
HAVING COUNT(*) = 2

我假设您的表具有适当的约束，因此不可能存在完全重复的行. (例如id, keyword上有一个PK)

I'm assuming that your table has appropriate constraints such that it is impossible for there to be a completely duplicated row. (e.g. there is a PK on id, keyword)

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