Question

I’ve been having a lot of difficultly recently getting the query result I want with my MySQL database – at the moment I’m not sure if the problem is with the database or the actual query.

Basically its a football player database with these tables:

(player): player_id (primary), playerName
(match): match_id (primary), playerID1, playerID2, playerID3, etc..

I want to query the database so that I am returned with the attributes in the match database, but the names of the players are returned rather than their ID’s.

I can get it to work for one player, but not the others. Here’s the code:

SELECT p.Name 
FROM `match` m
inner join `player` p on p.player_id=m.playerID1

But when I add the second player, p.Name is already mapped to playerID1 so it won’t work.

I suspect its the database which isn’t designed very well, but any recommendations are welcome!

Answer 1

That database design is causing your headaches. You should have decomposed the relationship between Match and Player by adding a MatchPlayer table that has both a MatchID and a PlayerID, thus allowing as many players as possible to be linked to a Match, without having to have a field for each one.

For your query though, you’ll have to do something like this:

SELECT p.Name 
FROM `match` m
INNER JOIN `player` p 
    ON p.player_id IN (m.playerID1, m.playerID2, m.playerID3) //etc

Demo SQLFiddle HERE