Question

I am using SQL Server 2008.

I am trying to do some basic math in some basic queries. I need to add up wins, losses, total, and percentages. I usually ask for the raw numbers and then do the calculations once I return my query to page. I would like to give SQL Server the opportunity to work a little harder.

What I want to do is something like this:

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

Here’s what I am doing now:

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

What is the easiest, cleanest way to do simple math calculations like this in a query?

*EDIT: *

While I got some great answers, I didn’t get what I was looking for.

The scores that I will be calculating are for a specific team, so, my results need to be like this:

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

I tried a bunch of things, but don’t quite know what wrong. I am sure the JOIN part is where the problem is though. How do I bring these two resultsets together?

Answer 1

One way is to wrap your query in an external one:

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 ...
)

Another way (suggested by @Mike Christensen) is to use Common Table Expressions (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 

---

Sidenote: No idea if this would mean any preformance difference in SQL-Server but you can also write these sums:

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

as counts:

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