SQL Server 存储过程添加两个声明的值总计
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SQL Server Stored Procedure add two declared values for total
提问by James
Here is what I have so far using two declared variables in the stored procedure:
到目前为止，我在存储过程中使用了两个声明的变量：
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)
How can I add @QuestionPoints and @EventPoints together to get the total points? Can I just add them using "+" and assigned to a third declared variable or have one overall statement?
如何将@QuestionPoints 和@EventPoints 相加以获得总分？我可以只使用“+”添加它们并分配给第三个声明的变量或有一个整体声明吗？
Thanks,
谢谢，
James
詹姆士
回答by RichardTheKiwi
If you don't need the two component variables anymore, you can (re)use one of the variables:
如果您不再需要这两个组件变量，您可以（重新）使用其中一个变量：
SET @QuestionPoints = ...
SET @EventPoints = ...
SET @QuestionPoints = @QuestionPoints + @EventPoints
Be careful though when adding SUM()'s, because they can be NULL. 20 + null => null. Use ISNULL if necessary, e.g.
但是在添加SUM()'s时要小心，因为它们可以是 NULL。 20 + null => null. 如有必要，请使用 ISNULL，例如
SET @QuestionPoints = isnull(@QuestionPoints, 0) + isnull(@EventPoints, 0)
If you still need them, then you can declare a third one.
如果您仍然需要它们，那么您可以声明第三个。
DECLARE @TotalPoints float --- or numeric or whatever the type should be
SET @TotalPoints = @QuestionPoints + @EventPoints
You could even skip the individual variables
您甚至可以跳过单个变量
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)
回答by Matthew Burr
If you need @QuestionPoints and @EventPoints to retain their current values, then yes, you need a third variable:
如果您需要 @QuestionPoints 和 @EventPoints 来保留它们的当前值，那么是的，您需要第三个变量：
DECLARE @totalPoints INT
SET @totalPoints = @QuestionPoints + @EventPoints
If you don't need them to retain their same value, then you can just overwrite one of them:
如果您不需要它们保留相同的值，那么您可以覆盖其中之一：
SET @QuestionPoints = @QuestionPoints + @EventPoints
SET @QuestionPoints = @QuestionPoints + @EventPoints
Or, in recent versions of SQL:
或者，在最新版本的 SQL 中：
SET @QuestionPoints += @EventPoints
SET @QuestionPoints += @EventPoints
回答by Thomas
You could do this in a single statement
你可以在一个语句中做到这一点
Set @Total = (
Select Sum( Z.points )
From (
Select points
From tb_responses
Where userid = @UserId
And Id = @Id
Union All
Select E.points
From dbo.tb_attendance As A
Join dbo.tb_events As E
On E.dbid = A.eventid
Where A.userid = @UserId
And A.didattend = 'Y'
And E.Id = @ID
) As Z
)
