对SQL Server中的子查询求和

Question

我有一个查询里面有一些子查询，我想添加一个求和查询来对它们进行求和。
我怎么能这样做？

示例：

Id,
(SELECT COUNT(*) FROM table1 LEFT JOIN table2 on ...) as col1,
(SELECT COUNT(*) FROM table3 LEFT JOIN table4 on ...) as col2,
** Sum of both col1 and col2 here **

Answer 1

试试这个：

SELECT ID, col1, col2, [Total] = (col1 + col2)
FROM (
    SELECT Id,
    (SELECT COUNT(*) FROM table1 LEFT JOIN table2 on ...) as col1,
    (SELECT COUNT(*) FROM table3 LEFT JOIN table4 on ...) as col2
    FROM [TABLE]) T

希望有所帮助。

Answer 2

最简单的方法是将所有查询视为子查询

select Id, col1 + col2 as total
from
(<yourCode>) s

因为在select子句中不能在相同的“查询级别”中使用别名。