Group values by a common value: userid and ipaddress

Question

I\'m working on a problem in my database. I\'m trying to find the users who are using multiple accounts. I have a list of user IDs and used IP addresses, like this:

Us

Answer 1

Use GROUP_CONCAT()

SELECT user_id, GROUP_CONCAT(DISTINCT ip_address SEPARATOR ', ') 
FROM TABLE_NAME GROUP BY user_id