Question

I’m making a PHP battle system, and need to sort out the ranking.

How I want it to work is say there’s 100 players, and you’re rank 90. You can challenge players 5 ranks above, so say you challenge and beat the player in rank 85, then YOU become 85 and he becomes 86.

I’m not sure how to do this with a database though. How to set it out, or store rank. Obviously I can’t save a field with your ‘rank’ since if you win it’d have to edit every single players rank below you in the database, wouldn’t it?

Any ideas would be helpful.

Answer 1

I recommend you do keep a rank field and relax the bottleneck in the queries:

In your example use something like

UPDATE players 
SET rank=IF(playerid=<id-of-challengin-player>,rank-5,rank+1) 
WHERE rank>=85 AND rank<=90

This will change ranks

old   new
85    86
86    87
87    88
88    89
89    90
90    85

which looks like what you want, but uses a single query, that can leverage an index and touches only 6 rows.

Edit

To facilitate maintenance (fix rank numbers, if there are holes etc.), run

CREATE VIEW players_by_rank AS 
SELECT * FROM players ORDER BY rank 

once, then use

UPDATE (SELECT @newrank:=0) AS init, players_by_rank 
SET score=(@newrank:=@newrank+1)

to close gaps in the table. Mind that this touches all rows!