mySQL SELECT join, group by or something

Question

hi There,

I can't get on the right track with this, any help would be appreciated

I have one table

+---+----------+---------+-----------+
|id | match_id | team_id | player_id |
+---+----------+---------+-----------+
| 1 |        9 |      10 |         5 |
| 2 |        9 |      10 |         7 |
| 3 |        9 |      10 |         9 |
| 4 |        9 |      11 |        12 |
| 5 |        9 |      11 |        15 |
| 6 |        9 |      11 |        18 |
+---+----------+---------+-----------+

I want to select these with a where on the match_id and both team id's so the output will be

+---------+-------+------+---------+---------+
| MATCHID | TEAMA | TEAMB| PLAYERA | PLAYERB |
+---------+-------+------+---------+---------+    
|       9 |    10 |   11 |       5 |      12 |
|       9 |    10 |   11 |       7 |      15 |
|       9 |    10 |   11 |       9 |      18 |
+---------+-------+------+---------+---------+

It's probably very simple, but i'm stuck..

thanks in advance

p.s. seemed to forgot a column on my first post, sorry

Answer 1

I think you need:

SELECT
    a.match_id, a.team_id AS TeamA, b.team_id AS teamB, 
    a.player_id AS PlayerA, b.player_id AS PlayerB
FROM PLayer AS a
    INNER JOIN Player AS b ON a.match_id = b.match_id
WHERE a.team_id < b.team_id

Though this will give you every pair of players for each game, i.e.

+---------+-------+------+---------+---------+
| MATCHID | TEAMA | TEAMB| PLAYERA | PLAYERB |
+---------+-------+------+---------+---------+    
|       9 |    10 |   11 |       5 |      12 | 
|       9 |    10 |   11 |       5 |      15 |
|       9 |    10 |   11 |       5 |      18 |
|       9 |    10 |   11 |       7 |      12 |
|       9 |    10 |   11 |       7 |      15 |
|       9 |    10 |   11 |       7 |      18 |
|       9 |    10 |   11 |       9 |      12 |
|       9 |    10 |   11 |       9 |      15 |
|       9 |    10 |   11 |       9 |      18 |
+---------+-------+------+---------+---------+

To restrict it further, you need a criterion to determine players should be paired.

Answer 2

I think it's better to redesign your database.

Answer 3

select MatchA.id as MATCHID, MatchA.team_id as TEAMA, MatchB.team_id as TEAMB, MatchA.player_id as PLAYERA, MatchB.player_id as PLAYERB
from Match as MatchA, match as MatchB 
where MatchA.id = MatchB.id and MatchA.team_id < MatchB.team_id