sql - 列到 MySql 中行的简单枢轴

Question

我在 mysql 中有下表:

A B C D
1 2 3 4

我想把它变成

<title1> <title2>
A        1
B        2
C        3
D        4

我只发现了复杂的东西，有谁知道一个简单的 staright forward 函数可以做到这一点吗？

Answer 1

select 'A' as title1, a as title2 from table union all
select 'B' as title1, b as title2 from table union all
select 'C' as title1, c as title2 from table union all
select 'D' as title1, d as title2 from table