Question

I’m trying to fetch statistics to an user for a game application but need help with making it to work with out having to make more then one query.

This is how it looks at the moment in short:
Table: userid(X int), outcome(win and loss), race (A, B and C)

I need now to fetch the count of win and loss for each race:

Select count(outcome) as win from games where userid = X and outcome = 'win' AND race = A

Select count(outcome) as loss from games where userid = X and outcome = 'loss' AND race = A

Select count(outcome) as win  from games where userid = X and outcome = 'win' AND race = B 

Select count(outcome) as loss from games where userid = X and outcome = 'loss' AND race = B

Select count(outcome) as win from games where userid = X and outcome = 'win' AND race = C 

Select count(outcome) as loss from games where userid = X and outcome = 'loss' AND race = C 

Then i basically calculates them in php after that but this is ridiculously slow approach when a large number of games is in the database.

So i basically want to have an query that groups by race like this:

Race | Win | Loss

A_____x_____x

B_____x_____x

C_____x_____x

I’m quite new to more complex forms of SQL so any suggestions on optimize this query would be helpful.

Thank you.

Answer 1

SELECT race, 
       COUNT(CASE 
               WHEN outcome = 'win' THEN 1 
             END) AS win, 
       COUNT(CASE 
               WHEN outcome = 'loss' THEN 1 
             END) AS loss 
FROM   games 
WHERE  userid = X 
       AND race IN ( 'A', 'B', 'C' ) 
GROUP  BY race