A somewhat complex mysql query - php

Question

I'm currently working on a news database website and I can't seem to create a query to select the 5 hottest news articles. The 2 tables of the database that are affected for this query are:
News - containing all news items (id, author, message, etc.)
Rates - containing all ratings on news items (id, news_id, rating, etc.)
Now my query should select 5 news_ids from the table Rates with the highest average rating and most votes ( so: ordered by AVG(Rating) and COUNT(*) I supposed ). I first tried to make my query as well get all info of these news_ids from the News table instantly ( using a WHERE id IN(--the query selecting the 5 hottest news_ids--) clause ) but that returned an error of my MySql Version not being cappable of using LIMIT inside of the WHERE IN clause sub-query.
Well, I hope you can help me out on the first query that has to select those 5 news_ids. The query I got as for now ( but not fully working ) is:
SELECT news_id FROM
(SELECT news_id, AVG(rating) AS average_r, COUNT(*) AS amt_r
FROM rates
GROUP BY news_id
ORDER BY average_r,amt_r
DESC LIMIT 5
) AS news_rates
or in content with the rest of my script:
$get_hot_news_ids = mysql_query("SELECT news_id FROM
(SELECT news_id, AVG(rating) AS average_r, COUNT(*) AS amt_r
FROM rates
GROUP BY news_id
ORDER BY average_r,amt_r DESC LIMIT 5) AS news_rates");
$first = 1;
while($news_id = mysql_fetch_assoc($get_hot_news_ids)) {
if(!$first) {
$hot_news_ids .= " ,";
}else{
$first = 0;
}
$hot_news_ids .= $news_id['news_id'];
}
//print_r($hot_news_ids);
$get_hot_news = mysql_query("SELECT * FROM news
WHERE id IN($hot_news_ids)
ORDER BY FIELD(id, $hot_news_ids)");

Answer 1

Are you sure both average_r and amt_r are both in descending order?
SELECT news_id FROM
(SELECT news_id, AVG(rating) AS average_r, COUNT(*) AS amt_r
FROM rates
GROUP BY news_id
ORDER BY average_r DESC, amt_r DESC
LIMIT 5
) AS news_rates

Answer 2

Try this:
SELECT TOP 5 N.id, N.author, N.message, AVG(R.rating) AS rate, COUNT(R.news_id) AS votes
FROM news N
INNER JOIN rates R ON N.id = R.news_id
GROUP BY N.id, N.author, N.message
ORDER BY rate, votes

Answer 3

You can use a join instead, which will allow the limit:
SELECT *
FROM news n JOIN (
SELECT news_id, AVG(rating) AS average_r, COUNT(*) AS amt_r
FROM rates
GROUP BY news_id
ORDER BY average_r,amt_r DESC
LIMIT 5
) top5 ON n.news_id = top5.news_id
ORDER BY top5.average_r,top5.amt_r
Note: You might want to change your query to a ORDER BY average_r DESC, amt_r DESC to get the highest rated items, instead of the lowest rated.