Question

This statement below gets me some data I need.

select TankName, COUNT(*) as Tanks, sum(Battles) as Battles, 
   SUM(victories) as Victories
from MemberTanks
where Tier = 9 and Class = 'Medium'
group by TankName
order by Tanks desc

I would like to show the percentage of the Victories in the resultset but I’m not sure how to do it. I tried…

select TankName, COUNT(*) as Tanks, sum(Battles) as Battles, 
   SUM(victories) as Victories, SUM(Victories)/SUM(Battles) as Percentage
from MemberTanks
where Tier = 9 and Class = 'Medium'
group by TankName
order by Tanks desc

… but percentage came back as “0” for every row.

How can I best get this value?

Answer 1

When you are calculating the percentage column since SUM(X) is returning a INT value, the result is getting floored and hence returning 0 as floored result

Multiply the SUM(victories) with a decimal value like 1.0 (so as to convert one operand to decimal/numeric) and then you would get correct result.

Try this:

SELECT TankName, 
    COUNT(*) as Tanks, 
    SUM(Battles) as Battles, 
  SUM(victories) as Victories,
    SUM(victories) * 1.0/ SUM(Battles) AS Percentage
 FROM MemberTanks
WHERE Tier = 9 
  AND Class = 'Medium'
GROUP BY TankName
ORDER BY Tanks desc

Also, if you are using SQL Server 2005 or above you can reduce the calculations.computations using a CTE like below:

WITH qry AS
(
    SELECT TankName, 
        COUNT(*) as Tanks, 
        SUM(Battles) as Battles, 
        SUM(victories) as Victories
     FROM MemberTanks
    WHERE Tier = 9 
        AND Class = 'Medium'
    GROUP BY TankName
)
SELECT a.*,
                Victories * 1.0 / Battles AS Percentage
  FROM qry a
ORDER BY Tanks DESC