SQL-具有来自2个表的条件的行总和 [英] SQL - Row sum with condition from 2 tables

问题描述

我有2个表，并且想从2个表中获取有条件的行总和. 这是我的桌子:

I have 2 tables and want to get the row sum from 2 tables with conditions. Here are my tables:

tabale1 ， tabale2

我想要2个表的行总和，例如:

i want the row sum from 2 tables, like:

if sk not null sum sk but if it is null sk = ss 

例如，sh2的总和为:19 + 5 + 11 + 5 = 40

For example, the total sum of sh2 is: 19 + 5 + 11 + 5 = 40

我真的很需要，请帮忙！

I really need that, please help!

表1:

表2:

推荐答案

下一个sql将返回表中的总和，并按名称分组:

Next sql will return the sum over the tables, grouping by name:

select name, sum(total) total from 
(select name, sum(coalesce(sk,ss)) total
 from table1
 group by name
 union all
 select name, sum(coalesce(sk,ss)) total
 from table2
 group by name
) t
group by name

子查询中的分组依据"子句非常重要，因为表是否返回很多行，它们将减少查询中分组依据"的行数，从而优化了时间并减少了内存使用.

The clause "group by" inside of the subqueries is very important because whether the tables return a lot of lines, they will reduce the number of lines for the "group by" on the query, optimizing time and using less memory.

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