透视表SQL

Question

我有这张桌子：

|............id.............|............a............. |.............b............|
|...........123qwe....      |...........0.............  |.............13...........|

我需要像这样枢纽一下：

|.........id................|........indicator....      |.............value........ |
|...........123qwe....      |...........a.............  |.............0.............|
|...........123qwe....      |...........b.............  |.............13........... |

超过100列带有指示符的标头（a，b，c，d，e，f，...），因此将需要某种循环。

Answer 1

 SELECT id, 'a', SUM(a)
 FROM yourtable
 GROUP BY id
 UNION 
 SELECT id, 'b', SUM(b)
 FROM yourtable
 GROUP BY id
 UNION
 ...

像往常一样， 正确的答案是规范您的架构。

Answer 2

像这样做：

SELECT id, 'a' AS indicator, a AS value
FROM test
UNION
SELECT id, 'b' AS indicator, b AS value
FROM test;

如果要循环，最好将其编写在程序中...