MYSQL如何对两个连接字段求和

【问题标题】：MYSQL how to sum of two concatenated fieldsMYSQL如何对两个连接字段求和
【发布时间】：2015-07-29 02:28:59
【问题描述】：

您好，您知道如何对两个已定义的字段求和吗？这可能吗？

SELECT SUM(a) as total_a, SUM(b) as total_b, (total_a + total_b) as grand_total
FROM table

如果没有，我怎么能想出这个？

【问题讨论】：

标签： mysql sum

【解决方案1】：

你也可以像这样内联：

SELECT SUM(a) as total_a, SUM(b) as total_b, (sum(a) + sum(b)) as grand_total
FROM table

【讨论】：

更简单：SELECT SUM(a) as total_a, SUM(b) as total_b, SUM(a + b) as grand_total FROM table.

【解决方案2】：

您需要创建一个子查询。

SELECT sum_ab.total_a + sum_ab.total_b as grand_total
FROM 
  (SELECT SUM(a) as total_a, SUM(b) as total_b
   FROM table
  ) as sum_ab

【讨论】：