Question

I don’t have much experience with SQL and I’m pretty much lost when it comes to anything more advanced than simple INSERT/SELECT statements.

My scenario is this, I have the following two tables:

Games
{
int id, int finished
}

Submissions
{
int game_id,int user_id
}

And I want to query any id from Games where finished=0 and a specific user_id is not tied together with the id in mind in the Submissions table.

So in other words, I want to find a game that isn’t finished and a specific user haven’t played.

I know I can do this with multiple queries and logic (in java and jdbc if it matters), but I rather learn how to do it with pure SQL!

Thanks!

Answer 1

SELECT g.id
FROM   Games g
WHERE  finished = 0
       AND NOT EXISTS(SELECT *
                      FROM   Submissions s
                      WHERE  s.user_id = @userid
                             AND s.game_id = g.id)  

Or (If your RDBMS supports it)

SELECT id
FROM   Games
WHERE  finished = 0
EXCEPT
SELECT game_id
FROM   Submissions
WHERE  user_id = @userid