MySQL SELECT DISTINCT 多列 [英] MySQL SELECT DISTINCT multiple columns

问题描述

假设我在 MySQL 数据库的一个表中有 a, b c, d 列.我想要做的是在我的表中选择所有这 4 列的不同值(只有不同​​的值).我试过这样的东西:

Let's say I have columns a, b c, d in a table in a MySQL database. What I'm trying to do is to select the distinct values of ALL of these 4 columns in my table (only the distinct values). I tried stuff like:

SELECT DISTINCT a,b,c,d FROM my_table;
SELECT DISTINCT a,b,c,d FROM my_table GROUP BY a,b,c,d;

那些都没有用.有人可以帮忙吗?

None of those worked. Can anybody help out here?

谢谢

注意 我想要分别列 a, b, c d 的不同值.不是值的不同组合

NOTE I want the distinct values of the columns a, b, c d separately. Not the distinct combination of values

推荐答案

这有帮助吗?

select 
(SELECT group_concat(DISTINCT a) FROM my_table) as a,
(SELECT group_concat(DISTINCT b) FROM my_table) as b,
(SELECT group_concat(DISTINCT c) FROM my_table) as c,
(SELECT group_concat(DISTINCT d) FROM my_table) as d

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