Selecting and aggregating multiple rows in MySQL

Question

I have a query that returns several rows that I'd like to group by a column. So for example,

title  | label
--------------
may      ny
may      ct
june     ma
june     ri

How would I (efficiently) return

title  | label
--------------
may      ct,ny
june     ma,ri

such that the ordering of the concatenation is alphabetical?

Answer 1

Check the GROUP_CONCAT function. The query would be:

SELECT title, GROUP_CONCAT(label ORDER BY label)
GROUP BY title