MySQL的合并列

Question

说我有以下MySQL的 '订单' 表：

id|car|car_qty|speakers|speakers_qty 
1 | 2 | 15 | 5 | 16 
2 | 2 | 19 | 5 | 40 

什么是查询来获取以下内容：使用UNION

product|qty 
    2 | 15 
    2 | 19 
    5 | 16 
    5 | 40 

无？

谢谢！

Answer 1

做一个工会都来自同一个表...只是需要确保列名和数据类型是相同的......

select 
     car as product, 
     car_qty as qty 
    from 
     orders 
union all 
select 
     speakers as product, 
     speakers_qty as qty 
    from 
     orders; 

Answer 2

试试这个：

SELECT car product,car_qty qty FROM orders 
UNION 
SELECT speakers product,speakers_qty qty FROM orders