Question

I am attempting to get the information from one table (games) and count the entries in another table (tickets) that correspond to each entry in the first. I want each entry in the first table to be returned even if there aren’t any entries in the second. My query is as follows:

SELECT g.*, count(*)  FROM games g, tickets t  WHERE (t.game_number = g.game_number    OR NOT EXISTS (SELECT * FROM tickets t2 WHERE t2.game_number=g.game_number)) GROUP BY t.game_number; 

What am I doing wrong?

Answer 1

You need to do a left-join:

SELECT g.Game_Number, g.PutColumnsHere, count(t.Game_Number)  FROM games g LEFT JOIN tickets t ON g.Game_Number = t.Game_Number GROUP BY g.Game_Number, g.PutColumnsHere 

Alternatively, I think this is a little clearer with a correlated subquery:

SELECT g.Game_Number, G.PutColumnsHere,   (SELECT COUNT(*) FROM Tickets T WHERE t.Game_Number = g.Game_Number) Tickets_Count FROM Games g 

Just make sure you check the query plan to confirm that the optimizer interprets this well.