从同一表中列出mysql中的结果 [英] list results in mysql from the same table

问题描述

我如何从此表中列出iduser，其中gender = man和int = woman?

How can i list the iduser from this table where gender=man and int=woman?

Table usermeta
----------------------
id  iduser a        b
12  204    age      19
7   203    age      35
6   200    age      24
3   201    age      34
5   201    gender   man
2   200    gender   woman
8   203    gender   man
9   204    gender   man
4   201    int      woman
10  204    int      male
11  203    int      woman
1   200    int      male

答案应该是:

iduser

204

我还有一个问题，如果我也想过滤年龄怎么办? 我正在尝试解决此问题，但我不能... 我应该在哪里放年龄= 19"? 我试试这个... a ='年龄' AND a.b ='19' 但是不工作... 谢谢.

I have another question, what if i want filter the age too? I'am trying to resolve this but i can't... Where shopuld i put the "age=19"? I try this... a.a = 'age' AND a.b = '19' but dont work... thanks.

推荐答案

自连接应该起作用.有点像(未经测试的):

A self join should work. Someting like (untested):

SELECT a.`iduser` FROM `table` a 
JOIN `table` b ON b.`iduser` = a.`iduser` 
WHERE a.`a`='gender' AND a.`b`='man' AND b.`a`='int' AND b.`b`='woman'

但是您应该考虑优化db结构，因为这似乎有点性能不足.

But you should consider to optimize the db structure since this seems a little performace hungry.

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