Resolving ties in MySQL rankings

Question

I have a MySQL table that looks something like this:

GOALS
------------------------
   PLAYER   |   GOALS
------------------------
     001    |    30
     002    |    25
     003    |    25
     004    |    20

I want to have a rank-based scoring system that gives half-points for ties. In the above example, it should look like this:

GOALS
-----------------------------------
   PLAYER   |   GOALS   |   SCORE
-----------------------------------
     001    |    30     |    4
     002    |    25     |    2.5
     003    |    25     |    2.5
     004    |    20     |    1

In case of a three-way tie:

GOALS
-----------------------------------
   PLAYER   |   GOALS   |   SCORE
-----------------------------------
     001    |    30     |    5
     002    |    25     |    3
     003    |    25     |    3
     004    |    25     |    3
     005    |    20     |    1

How would something like this be done in mySQL?

Thanks!

Answer 1

SELECT a.player, a.goals, (SUM(a.goals > b.goals) + 1 + SUM(a.goals >= b.goals))/2 AS score
FROM goals a
CROSS JOIN goals b
GROUP BY player

DEMO

This works because SUM(a.goals > b.goals) + 1 is the minimum rank of all the tied players, while SUM(a.goals >= b.goals) is the maximum rank. So this averages the two ends of the range to get the score.