sql - SQL Server存储过程为总数添加两个声明的值

Question

到目前为止，这是我在存储过程中使用两个声明的变量的结果:

SET @QuestionPoints = (SELECT SUM(points) 
                       FROM   tb_responses 
                       WHERE  userid = @UserId 
                              AND id = @ID) 
SET @EventPoints =(SELECT SUM(dbo.tb_events.points) 
                   FROM   dbo.tb_attendance 
                          INNER JOIN dbo.tb_events 
                            ON dbo.tb_attendance.eventid = dbo.tb_events.dbid 
                   WHERE  dbo.tb_attendance.userid = @UserID 
                          AND dbo.tb_attendance.didattend = 'Y' 
                          AND dbo.tb_events.id = @ID) 

如何将@QuestionPoints和@EventPoints加在一起以得到总积分？我可以仅使用“+”将它们添加并分配给第三个声明的变量，还是可以有一个整体语句？

谢谢，

詹姆士

Answer 1

如果您不再需要两个组成变量，则可以(重新)使用其中一个变量:

SET @QuestionPoints = ...
SET @EventPoints = ...
SET @QuestionPoints = @QuestionPoints + @EventPoints 

不过，在添加 SUM()时要小心，因为它们可以为NULL。 20 + null => null。如有必要，请使用ISNULL，例如

SET @QuestionPoints = isnull(@QuestionPoints, 0) + isnull(@EventPoints, 0)

如果仍然需要它们，则可以声明第三个。

DECLARE @TotalPoints float  --- or numeric or whatever the type should be
SET @TotalPoints = @QuestionPoints + @EventPoints 

您甚至可以跳过各个变量

SET @QuestionPoints = (SELECT SUM(POINTS) FROM tb_Responses WHERE UserID = @UserId AND ID = @ID)
                      +
                      (SELECT SUM(dbo.tb_Events.Points) FROM  dbo.tb_Attendance INNER JOIN   dbo.tb_Events ON dbo.tb_Attendance.EventID = dbo.tb_Events.dbID WHERE dbo.tb_Attendance.UserID = @UserID AND dbo.tb_Attendance.DidAttend = 'Y' AND dbo.tb_Events.ID = @ID)