相关疑难解决方法(0)

让我们假设下表(例如几个内连接语句的结果):

id | column_1 | column_2
------------------------
 1 |  1       | 
 2 |  2       | 2
 3 |          | 3

例如,您可以从以下语句中获取:

select a.id, t1.column_1, t2.column_2
from a
left join t1 on a.id = t1.id
left join t2 on a.id = t2.id

现在,如果我想总结t1.column_1和t2.column_2,如下所示

select 
    a.id, 
    t1.column_1, 
    t2.column_2,
    (t1.column_1 + t2.column_2) as cumulated
from a
left join t1 on a.id = t1.id
left join t2 on a.id = t2.id

reslut将如下所示:

id | column_1 | column_2 | cumulated
------------------------------------
 1 |  1       | …