MYSQL 选择两列中的 DISTINCT 值 [英] MYSQL select DISTINCT values in two columns

问题描述

我想在数据库中选择不同的值.让我通过一个简单的例子来告诉你.

I want to select distinct values in a database. Let me run you through a quick example.

表格:

foo bar
--- ---
a   c
c   f
d   a
c   a
f   c
a   c
d   a
a   c
c   a
f   c

好吧，假设我的 SQL 是 SELECT DISTINCT foo, bar from table.这些是我的结果:

Right, let's say my SQL is SELECT DISTINCT foo, bar from table. These are my results:

foo bar
--- ---
a   c
c   f
d   a
c   a
f   c

然而，问题是存在 a c/c a 的重复，只是它们的顺序不同.我不想选择这些，我想要两列的不同值，请帮忙！

However the problem is is that there are repetitions of a c / c a just that they are in a different order. I don't want to select these, I want distinct values from both columns, please help!

推荐答案

非常非常邪恶 &邪恶:

very very wicked & evil:

select distinct
    least(foo, bar) as value1
  , greatest(foo, bar) as value2
from table

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