sql - 在 SQL Server 中添加两个值

Question

我想在一个语句中添加两个值，目前我不知道如何去做，这应该很简单，这是我的语句:

 SELECT COUNT(UserModified) as SecondTally
 FROM JobAgents 
 WHERE UserModified = 1

然后从下面的值中减去上面的值。

 SELECT SUM(EmailsSent) as FirstTally
 FROM JobAgentEmails
 WHERE Date BETWEEN '7/1/2012 12:00:00 AM' AND '7/31/2012 11:59:59 PM'

如有任何帮助，我们将不胜感激。非常感谢。

Answer 1

最简单的方法是简单地将结果与两个子查询结合起来，这两个子查询可以存储在变量中，也可以简单地结合在一个查询中，如下所示:

SELECT
  (SELECT SUM(EmailsSent) as FirstTally
   FROM JobAgentEmails
   WHERE Date BETWEEN '7/1/2012 12:00:00 AM' AND '7/31/2012 11:59:59 PM')
- (SELECT COUNT(UserModified) as SecondTally
   FROM JobAgents 
   WHERE UserModified = 1)