更优雅的方式在列上执行数学运算

Question

有更优雅的方式这样做:

SELECT TOP (@NumOfGames) 
        (SUM(IIF(Fixture.HomeTeamID = @Team
            ,IIF(Fixture.Goals.FullTimeHomeGoals > Fixture.Goals.FullTimeAwayGoals
                    ,1 
                    ,IIF(Fixture.Goals.FullTimeHomeGoals < Fixture.Goals.FullTimeAwayGoals, 0, 0.5) 
                ) --IsHomeTeam
            ,IIF(Fixture.Goals.FullTimeAwayGoals > Fixture.Goals.FullTimeHomeGoals
                    ,1 
                    ,IIF(Fixture.Goals.FullTimeAwayGoals < Fixture.Goals.FullTimeHomeGoals, 0, 0.5) 
                ) --IsAwayTeam
        )) / @NumOfGames) * 100 AS Result
    FROM 
        Fixture.Fixture 
    INNER JOIN 
        Fixture.Goals ON Fixture.Goals.FixtureID  = Fixture.Fixture.FixtureID
    WHERE 
        HomeTeamID = @Team 
        OR 
        AwayTeamID = @Team 

我非常讨厌SUM部分,必须有更好的方法来做到这一点.

用户输入@NumOfGames和@Team作为存储过程的参数.然后它会检查目标表,看看一支球队是赢了,是否赢了.胜利是1分,平局是0.5,损失是0.我想输出这些数字的总和,除以NumOfGames并乘以100得到成功率.

Answer 1

呸.Microsoft似乎已将IIF添加到SQL Server 2012中.无论如何,您可能会发现标准SQL方式更具吸引力.这将使用CASE语句:

SELECT TOP (@NumOfGames) 
       (SUM(case when Fixture.HomeTeamID = @Team and
                      Fixture.Goals.FullTimeHomeGoals > Fixture.Goals.FullTimeAwayGoals
                 then 1.0
                 when Fixture.HomeTeamID = @Team and
                      Fixture.Goals.FullTimeHomeGoals = Fixture.Goals.FullTimeAwayGoals
                 then 0.5
                 when Fixture.HomeTeamID = @Team
                 then 0.0
                 when Fixture.HomeTeamID <> @Team and
                      Fixture.Goals.FullTimeAwayGoals > Fixture.Goals.FullTimeHomeGoals
                 then 1.0
                 when Fixture.HomeTeamID <> @Team and
                      Fixture.Goals.FullTimeAwayGoals = Fixture.Goals.FullTimeHomeGoals
                 then 0.5
                 else 0.0
        end) / @NumOfGames) * 100 AS Result
FROM 
    Fixture.Fixture 
INNER JOIN 
    Fixture.Goals ON Fixture.Goals.FixtureID  = Fixture.Fixture.FixtureID
WHERE 
    HomeTeamID = @Team 
    OR 
    AwayTeamID = @Team 

对于记录,在case语句中不需要比较"Fixture.HomeTeamID <> @Team",只是为了使它更具可读性(而且效率更低).case语句的工作原理是按顺序评估WHEN子句,然后选择匹配的第一个子句.

我们可以请求微软删除IIF()吗？;-)