Question

I have one table GAMES and another PLAYERS. Currently each “game” has a column for players_in_game but I have nothing reciprocating in the PLAYERS table. Since this column is an array (Comma separated list of the player’s ID #s) I’m thinking that it would probably be better to have each player’s record also contain a list of the games they are a member of. On the other hand, duplicating the information in two separate tables might actually require more DB calls.

For perspective, there aren’t likely to be more then a dozen players in a game (generally 4-6 is the norm) but there could potentially be a large number of games.

Is there a good way to figure out which would be more efficient?
Thanks.

Answer 1

Normalization is generally a good thing. Comma delimited lists in tables is a sign that a table is in desperate need of a foreign key. If you’re worried about extra queries, check out JOINING

dbo.games
+----+----------+
| id |   name   |
+----+----------+
| 1  |    war   |
| 2  | invaders |
+----+----------+

dbo.players
+----+----------+---------+
| id |   name   | game_id |
+----+----------+---------+
| 1  |   john   |    1    |
| 2  |   mike   |    1    |
+----+----------+---------+

SELECT games.name, count(players.id) as total_players FROM games INNER JOIN players ON games.id = players.game_id GROUP BY games.name;

Result:
+-----------+--------------+
| name      |total_players |
+-----------+--------------+
| war       |       2      |
| invaders  |       0      |
+-----------+--------------+

Sidenote: Go Hokies 🙂