How to write sql statement for following scenario? So I currently have an sql statement: 

Select room_no, category from help_desk where room_no = '133' OR room_no = '120';


and it returns: 



How would I write an sql statement that would return it like this
You need to use three things


GROUP BY
GROUP_CONCAT
DISTINCT within GROUP_CONCAT


Here is such a query

Select room_no, group_concat(distinct category) categories
from help_desk where room_no in (133,120) group by room_no;