Question

I have this query that I’m running against mysql:

SELECT video.title AS title, 
       video.url AS url, 
       video.id AS id, 
       video.description AS description,
       avg(BodyPartsVideosUser.rating) AS rating 
FROM videos AS video  
   LEFT JOIN body_parts_videos as BodyPartsVideo on BodyPartsVideo.video_id = video.id 
   LEFT JOIN  body_parts_videos_users as BodyPartsVideosUser on BodyPartsVideo.id = BodyPartsVideosUser.body_parts_video_id 
WHERE BodyPartsVideo.body_part_id =  39  
GROUP BY BodyPartsVideosUser.body_parts_video_id 
ORDER BY rating DESC ;

Now, the problem is that I get back one row with this query.

However, my videos table has three totally distinct entries, and my body_parts_videos table has three entries corresponding to the videos table. However, the body_part_id column there is 39 for each entry.

the body_parts_videos_users table is empty.

How do i alter this query so i get all three row returned?

body_parts_videos:

+----+--------------+----------+
| id | body_part_id | video_id |
+----+--------------+----------+
|  1 |           39 |       26 |
|  3 |           39 |       28 |
|  4 |           39 |       29 |
+----+--------------+----------+

videos:

+----+---------+-------------+--------------------------------------+-------------+----------
| id | title   | description | user_id  | url         | filename | created    | modified   |
+----+---------+-------------+--------------------------------------+-------------+----------
| 26 | new vid | dd          | 1        | eMvu0Cbi040 | a.avi    | 2011-11-23 | 2011-11-23 |
| 28 | new vid | dd          | 2        | ETyBso2SHJM | b.avi    | 2011-11-23 | 2011-11-23 |
| 29 | title   | ddd         | 3        | 2Ud41iWKUIg | c.avi    | 2011-11-23 | 2011-11-23 |
+----+---------+-------------+--------------------------------------+-------------+----------

body_parts_videos_users:
empty

I want to select from the empty body_parts_videos_users table because, when there are results, I want them to appear first. The empty row magically becomes zero somehow, but I’m fine with that.

Any ideas what I’m doing wrong? Oh! Here is what i get when i run the query:

+---------+-------------+----+-------------+--------+-
| title   | url         | id | description | rating | 
+---------+-------------+----+-------------+--------+-
| new vid | eMvu0Cbi040 | 26 | dd          |   NULL | 
+---------+-------------+----+-------------+--------+-

Here’s what i’d expect:

+---------+-------------+----+-------------+--------+-
| title   | url         | id | description | rating | 
+---------+-------------+----+-------------+--------+-
| new vid | eMvu0Cbi040 | 26 | dd          |   NULL | 
+---------+-------------+----+-------------+--------+-
| new vid | ETyBso2SHJM | 28 | dd          |   NULL | 
+---------+-------------+----+-------------+--------+-
| title   | 2Ud41iWKUIg | 29 | ddd         |   NULL | 
+---------+-------------+----+-------------+--------+-

Any help is much appreciated!

Answer 1

I think the problem is, that your body_parts_videos_users table is empty.
change your GROUP BY to GROUP BY body_parts_videos.body_part_id,body_parts_videos.video_id