Question

我必须在一个简单的查询中使用SELECT，UNIONed ...

SELECT description_x, a, b, c, d from table a WHERE person_id = 1
UNION
SELECT description_y, e ,f ,g ,h from table b WHERE person_id = 1

... a，b，c，d，e，f，g，h都是整数。我如何理解它们，结果看起来像这样...

row 1: description_x |  a  |  b  |  c  |  d
row 2: description_y |  e  |  f  |  g  |  h
row 3: summary       | a+e | b+f | c+g | d+h

...好吗？

非常感谢！

Answer 1

您可以向其添加另一个union来进行聚合。

select description_x, a, b, c, d from table a where person_id = 1
union all
select description_y, e ,f ,g ,h from table b where person_id = 1
union all
select 'summary', sum(a), sum(b), sum(c), sum(d) from (
    select a, b, c, d from table a where person_id = 1
    union all
    select e ,f ,g ,h from table b where person_id = 1
) t

如果MySQL支持的CTE（正如评论中提到的那样，将在MySQL 8之后推出），我们不需要再次重写相同的查询。

Answer 2

select sum(a) as a,sum(b) as b,sum(c) as c,sum(d) as d from (
SELECT description_x, a, b, c, d from table a WHERE person_id = 1
UNION All
SELECT description_y, e ,f ,g ,h from table b WHERE person_id = 1
)T

MySQL：SUM两个UNIONed表（一个结果中4x SUM）

2 个答案: