Say, you have a table named hobbies and wanted to display a list of hobbies based on user_id, you'd probably do something like this:

SELECT title FROM hobbies WHERE user_id = 8;

This would return a list of hobbies like this:

Boxing
Coding
Reading
Fishing

That's simple but what if you wanted to display them in one row? Like this:

Boxing, Coding, Reading, Fishing

You can make use of the GROUP_CONCAT method to achieve the same result by executing the following SQL query:

SELECT GROUP_CONCAT(title, SEPARATOR ', ') FROM hobbies WHERE user_id = 8;

Nice, what if you wanted to view a list of hobbies of all users? In most cases, a table like this might have a many-to-many relationship, so in order to avoid possible duplicates, you can try this:

SELECT user_id, GROUP_CONCAT(title, SEPARATOR ', ') FROM hobbies
GROUP BY user_id

Hope this tip helps you out!