Question

I have a query that ranks results in MySQL:

SET @rank := 0;
SELECT Name, Score, @rank := @rank + 1 
FROM Results 
ORDER BY Score

This works fine until I try to base the ranking on the average score:

SET @rank := 0;
SELECT Name, AVG(Score) as AvScore, @rank := @rank + 1 
FROM Results 
ORDER BY AvScore

If I run this I get just the one record back because of the AVG. However, if I add a GROUP BY on Name so that I can get the averages listed for everyone, this has the effect of messing up the correct rankings.

I know the answer’s probably staring me in the face but I can’t quite get it. How can I output a ranking for each name based on their average result?

Answer 1

You need to use a sub-query:

SET @rank := 0;

SELECT a.name, 
       a.avscore, 
       @rank := @rank + 1 
FROM   (SELECT name, 
               Avg(score) AS AvScore 
        FROM   results 
        GROUP  BY name) a
ORDER  BY a.avscore