Question

I have a table GAMES with this information:

- Id_Game (int)
- Id_Referee1 (int)
- Id_Referee2 (int)

These are some rows:

ID_GAME    ID_REFEREE1    ID_REFEREE2
1          1000           728
2          1004           813
3          728            1004
4          1004           1000

I want to have a list with the number of games that a referee has officiated, doesn’t matter if as a Referee1 or Referee2. In this case, I would like to receive this list order by number of games DESC.

REFEREE    NUMBER OF GAMES
1004       3
728        2
1000       2
813        1

Which would be the SQL query? I have no idea of how to join fields Id_Referee1 and Id_Referee2…

THANKS

Answer 1

I think:

select referee, count(*) from (
    select id_game, id_referee1 as referee
    from games
    union
    select id_game, id_referee2 as referee
    from games
)
group by referee