mysql - 自定义列的多个值

Question

我希望每个 ID 都有 2 个 Custom_Column 值。我该怎么做？

示例表:

ID
1
2
3

示例查询:

SELECT id, (id*2) as Custom_Value, (id*4) as Custom_Value FROM numbers

响应:

ID    Custom_Value
1     2
1     4
2     4
2     8
3     6
3     12

Answer 1

使用UNION

SELECT ID, (ID*2) as CustomVal FROM tableNAme
UNION ALL
SELECT ID, (ID*4) as CustomVal FROM tableNAme
ORDER BY ID

• SQLFiddle Demo