Question

This is eluding me. I am trying to pull meta data about players that I have matched against each other in a game. Eg: Player 22 vs. Player 54

I have 2 mysql tables.

Table: players (id, name, image_url, etc)

1 | John | john.jpg | etc
2 | George | george.jpg | etc
3 | Ian | ian.jpg | etc
4 | Steve | steve.jpg | etc

Table: matchups (id, left_players_id, right_players_id)

1 | 1 | 3
2 | 2 | 4

I want to display the left player image and name and the right player image and name on my web page.

SELECT m.left_players_id, p.name AS left_player, m.right_players_id, p.name AS right_player
FROM players p, matchups m
WHERE m.left_players_id = p.id
AND m.right_players_id = p.id

0 results because of the AND (requiring a match that doesn’t exist)

SELECT m.left_players_id, p.name AS left_player, m.right_players_id, p.name AS right_player
FROM players p, matchups m
WHERE m.left_players_id = p.id
OR m.right_players_id = p.id

4 results (dupes of each row)

What am I missing?

Answer 1

You need to join to the players table twice, once for each player.

SELECT m.left_players_id, l.name AS left_player, m.right_players_id, r.name AS right_player 
FROM players r, payers l, matchups m 
WHERE m.left_players_id = l.id AND m.right_players_id = r.id