Question

I’m getting a bit lost in making a query that performs a certain look up.
I have the first part of the query going, which returns me all accounts that have missing some entries on their account. Now I need to filter this subset further based on their last login attempt.

The table structures are as follows:

• The users table contains all user information. We only care about users under project_id 33.
• The users_account_list contains all accounts a user has. We only care about users NOT having an entry for service 50.
• The users_login_logs contains all login attempts for a user.

The original query I have this this:

SELECT u.id,
       u.login, 
       u.email, 
       u.nickname,
       b.station_login AS "additionals.station_login",
       a.id AS "user_account_list.id",
       a.game_id AS "user_account_list.game_id",
       a.game_uid AS "user_account_list.game_uid",
       c.created_at AS "last login"
FROM users u
LEFT JOIN user_account_list a ON u.id = a.user_id AND a.game_id = 50
LEFT JOIN user_additionals b ON u.id = b.id
LEFT JOIN user_login_logs c ON u.id = c.user_id
WHERE u.project_id = 33
AND u.verified_at IS NOT NULL
AND (a.id IS NULL OR a.game_id IS NULL OR a.game_uid IS NULL)
AND (b.station_login IS NULL OR b.station_login = '')
ORDER BY c.created_at DESC

This returns me all users that have been registered under project_id 33, and do not have an entry for game_id 50, and have no information stored in their additional info table. Optional, but not relevant, Just limits the data returned. It does give me multiple rows per user back , sorted according their latest login date.

What I need is to get only 1 row per user returned with their LATEST login date. I tried replacing the ORDER BY with GROUP by u.id but this gives me the oldest result back, not the latest.

How can I:

• Limit the rows returned to only 1 row per user
• Make sure the row is based on the latest login attempt of the user.

EDIT:

This is what the query currently returns:

+----+-------+-----------------+----------+---------------------------+----------------------+---------------------------+----------------------------+---------------------+
| id | login | email           | nickname | additionals.station_login | user_account_list.id | user_account_list.game_id | user_account_list.game_uid | last login          |
+----+-------+-----------------+----------+---------------------------+----------------------+---------------------------+----------------------------+---------------------+
|  1 | usrnm | [e-mail] | Nickname |                           |                 NULL |                      NULL | NULL                       | 2012-10-19 00:00:00 |
|  1 | usrnm | [e-mail] | Nickname |                           |                 NULL |                      NULL | NULL                       | 2012-10-18 00:00:00 |
|  1 | usrnm | [e-mail] | Nickname |                           |                 NULL |                      NULL | NULL                       | 2012-10-17 00:00:00 |
+----+-------+-----------------+----------+---------------------------+----------------------+---------------------------+----------------------------+---------------------+
3 rows in set (0.08 sec)

Answer 1

You need to replace your ORDER BY by a GROUP by u.id as you tried but you also need in your SELECT to indicate that you want the last date in the group so you need to replace

c.created_at AS "last login"

by

MAX(c.created_at) AS "last login"

This will return only one line per user thanks to the GROUP BY and you will only select the latest date for each user thanks to MAX()

Edit: I think you should avoid using alias column names with spaces inside to avoid mistakes