如何在查询中添加和划分别名列？

Question

我正在使用SQL Server 2008.

我试图在一些基本查询中做一些基本的数学运算.我需要加上胜利,损失,总数和百分比.我通常会询问原始数字,然后在将查询返回页面后再进行计算.我想让SQL Server有机会更努力地工作.

我想做的是这样的:

SELECT   SUM(case when vote = 1 then 1 else 0 end) as TotalWins,
         SUM(case when vote = 0 then 1 else 0 end) as TotalLosses,
         TotalWins + TotalLosses as TotalPlays,
         TotalPlays / TotalWins  as PctWins

这就是我现在正在做的事情:

SELECT   SUM(case when vote = 1 then 1 else 0 end) as TotalWins,
         SUM(case when vote = 0 then 1 else 0 end) as TotalLosses,
         SUM(case when vote = 1 then 1 else 0 end) + SUM(case when vote = 0 then 1 else 0 end) as Votes

在查询中进行简单数学计算的最简单,最干净的方法是什么？

*编辑:*

虽然我得到了一些很好的答案,但我没有得到我想要的东西.

我将计算的分数是针对特定团队的,因此,我的结果必须如下所示:

TeamID   Team    Wins   Losses  Totals
1        A's     5      3       8
2        Bee's   7      9       16
3        Seas    1      3       4

SELECT   T.TeamID,
         T.Team,
         V.TotalWins,
         V.TotalLosses,
         V.PctWins
FROM     Teams T 

      JOIN 

     SELECT  V.TeamID,
             SUM(case when vote = 1 then 1 else 0 end) as V.TotWin,
             SUM(case when vote = 0 then 1 else 0 end) as V.TotLoss
     FROM    Votes V
GROUP BY V.TeamID

我尝试了很多东西,但不太清楚什么是错的.我确信JOIN部分是问题所在.如何将这两个结果集组合在一起？

Answer 1

一种方法是将查询包装在外部查询中:

SELECT TotalWins,
       TotalLosses,
       TotalWins + TotalLosses as TotalPlays,
       TotalPlays / TotalWins  as PctWins
FROM
( SELECT SUM(case when vote = 1 then 1 else 0 end) as TotalWins,
         SUM(case when vote = 0 then 1 else 0 end) as TotalLosses
  FROM ...
)

另一种方式(由@Mike Christensen建议)是使用公用表表达式(CTE):

; WITH Calculation AS 
    ( SELECT SUM(case when vote = 1 then 1 else 0 end) as TotalWins,
             SUM(case when vote = 0 then 1 else 0 end) as TotalLosses
      FROM ...
    )

SELECT TotalWins,
       TotalLosses,
       TotalWins + TotalLosses as TotalPlays,
       TotalPlays / TotalWins  as PctWins
FROM
       Calculation 

旁注:不知道这是否意味着SQL-Server中的任何性能差异,但您也可以写下这些总和:

SUM(case when vote = 1 then 1 else 0 end)

作为计数:

COUNT(case when vote = 1 then 1 end)    --- the ELSE NULL is implied