splitting mysql result into seperate username with comma

Hi guys,

You see I'm trying to clean up my user database, by checking the last login time of my users. I got the results - all the usernames.

My question is how can I display the results with comma between each username?


SQL query:
SELECT `username`
FROM `u_users`
WHERE `is_activated` =1
AND `last_login_time` <1185926400
ORDER BY `userid` ASC
LIMIT 0 , 50

 

SELECT CONCAT(`username`, ',')
...

 

thanks a lot!