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