Question

I have a MySql table named ‘comments’ :

id | date       | movie_id | comment_value
1    2011/11/05   10         comment_value_1
2    2012/01/10   10         comment_value_2
3    2011/10/10   15         comment_value_3
4    2011/11/20   15         comment_value_4
5    2011/12/10   30         comment_value_5

And i try to have the most recent comment for each movie with the query :

SELECT MAX(date),id,date,movie_id,comment_value FROM comments GROUP BY movie_id

The MAX(date) return the most recent date, but the row associated (movie_id,id,comment_value,date) did not match. It returns the value of the first comment of the movie, like this :

MAX(date)  | id | date       | movie_id | comment_value
2012/01/10   1    2011/11/05   10         comment_value_1
2011/11/20   3    2011/10/10   15         comment_value_3
2011/12/10   5    2011/12/10   30         comment_value_5

So, my question is : how can i have the most recent comment for each movie, in only one query ( i’m actually using a second query to get the good comment)

Answer 1

Using two queries isn’t so bad. Otherwise you can do something like

SELECT id, date, movie_id, comment_value FROM comments c JOIN
(SELECT movie_id, MAX(date) date FROM comments GROUP BY movie_id) x
ON x.movie_id=c.movie_id AND x.date=c.date GROUP BY movie_id;