这是我到目前为止在存储过程中使用两个声明的变量：
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)
如何将@QuestionPoints和@EventPoints一起添加以获得总积分？我可以使用“”添加它们并分配给第三个声明的变量或者有一个整体声明吗？
谢谢,
詹姆士
解决方法
如果您不再需要这两个组件变量,则可以(重新)使用其中一个变量：
SET @QuestionPoints = ... SET @EventPoints = ... SET @QuestionPoints = @QuestionPoints + @EventPoints
添加SUM()时要小心,因为它们可以为NULL. 20 null =>空值.必要时使用ISNULL,例如
SET @QuestionPoints = isnull(@QuestionPoints,0) + isnull(@EventPoints,0)
如果你仍然需要它们,那么你可以宣布第三个.
DECLARE @TotalPoints float --- or numeric or whatever the type should be SET @TotalPoints = @QuestionPoints + @EventPoints
你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)
