I run a site where people can rate articles written by members (user_id). These articles can then be rated by others on a special scale.

TABLE: articles -
id | user_id | title
1 | 3 | Transformers
2 | 5 | Shrek
3 | 2 | Shrek

TABLE: article_ratings -
article_id | rating_x | rating_y
1 | 4 | 5
2 | 3 | 2
2 | 4 | 4
3 | 2 | 5
2 | 5 | 3
3 | 4 | 4

Basically what I'm trying to do is get the average of the averages for a specific article. Example: I want to know the average of the average ratings for all the articles on 'Shrek'

The Shrek article ID's are 2 and 3

The average rating for Shrek with ID:2 are:
rating_x = 4
rating_y = 3

The average rating for Shrek with ID:3 are:
rating_x = 2
rating_y = 3

Then average those both together to bring a result of:
rating_x = 3
rating_y = 3
^^^^^^^^^^ And this result just here is the kind of output I want my database to provide.

I'm able to get the averages alone but am not able to get the average of the averages. I'm using PHP and SQL if that helps.

I'm thinking something along the lines of:
SELECT AVG(AVG(article_ratings.rating_x)), AVG(AVG(article_ratings.rating_y )) FROM article_ratings, articles WHERE articles.title='Shrek' AND articles_rating.article_id=articles.id
Obviously, two AVG()'s overlapping aren't allowed and my SQL isn't great as you can see so I hope someone can help.

I think I understand what you're looking for, but not entirely sure Your original math didn't add up to mine using your table data, but try this:

PHP Code:

SELECT AVG(avgx), AVG(avgy) FROM 
      (SELECT AVG(article_ratings.rating_x) AS avgx, AVG(article_ratings.rating_y) AS avgy, articles.id AS id
         FROM article_ratings, articles 
         WHERE article_ratings.article_id=articles.id AND articles.title='Shrek' 
         GROUP BY articles.id) AS t1; 


Resulted in the following using your data:

PHP Code:

+------------+------------+
| AVG(avgx)  | AVG(avgy)  |
+------------+------------+
| 3.50000000 | 3.75000000 |
+------------+------------+ 


If I could buy you a drink over the internet, I would. Seriously, fantastic. Thanks so much.

You're very welcome! Best of luck to your web endeavor