Question

I don’t really know how to even search for resolution of this problem, didn’t find anything specific, so here goes…

I have four tables, let’s simplify them:

  players
  =======
  id    name    surname
  1     John    Arbuckle
  2     Walter  White
  3     Don Draper
  4     Louis   CK
  5     Tyrion  Lannister
  6     Abed    Nadir

  sports
  ======
  id    sport
  1     football
  2     handball

  positions
  =========
  id    name    sport_id
  1     goalie  1
  2     defense 1
  3     attack  1
  4     goalie  2
  5     pivot   2
  6     wing    2
  7     center  2

  player_position
  ===============
  player_id position_id
  1         1
  1         2
  1         5
  2         7
  2         5
  3         2
  4         2
  5         1
  5         3
  6         7
  6         5

So, player can play multiple sports and on multiple positions. First, I have to display list of players for a certain sport, including a column with positions they play.

What I started with is JOIN statement where I’d join those tables and have multiple rows for each player ID. That’s close, but not very correct. And what I need to get is a tables like this:

FOOTBALL

    ID  name    surname     position
    1   John    Arbuckle    PHP array(goalie,defense)

HANDBALL

    ID  name    surname     position
    1   John    Arbuckle    PHP array(pivot)

EDIT:
So what I was looking for was GROUP_CONCAT().
Thanks guys!

Answer 1

select p.id, p.name, p.surname, group_concat(po.name)
from players p 
inner join player_position pp on pp.player_id = p.id
inner join positions po on po.id = pp.position_id
inner join sports s on s.id = po.sport_id
where s.sport = 'football'
group by p.id

See this SQLFiddle example