Question

i have a problem with sql query.
I need to get list of users. The problem is the left join i use.
this is my query

 SELECT  
u.*  
 FROM  
users u LEFT JOIN game g on g.user_id = u.user_id  
LEFT JOIN game_actions ga on ga.game_id = g.id  
LEFT JOIN emails e on e.id = ga.email_id
WHERE  
u.user_id = 0  
AND u.is_contact_by_email = 1 
    AND email.type = 2

this query returns the same user more then once because of the join with other tables
i want this query to return each user just one time.
i’m using sql developer.

thanks in advanced.

Answer 1

I suppose there are more games, actions, and emails for each user. How do you imagine the result table to look like? Because when you are selecting only from user table (SELECT u.*), then there is no point in joining others. If you need the other tables, use GROUP BY (u.user_id) to group rows by user.