SQL: Two different queries to merge

Question

I have these two different queries.

This query pulls the records from "posts" table as per their replies counter. Only posts with replies are returned with this query:

SELECT posts.title, posts.num, posts.status, COUNT( posts_replies.post_num)  AS count
FROM posts_replies
INNER JOIN posts ON ( posts_replies.post_num = posts.num )
WHERE posts.status = 1
AND posts.category='uncategorized'
GROUP BY posts.num

And this is a new query that i want to merge with the above one to pull and sort records as per gps.

SELECT num, title, ( 3959 * acos( cos( radians( 37 ) ) * cos( radians( lat ) ) * cos( radians( lon ) - radians( -122 ) ) + sin( radians( 37 ) ) * sin( radians( lat ) ) ) ) AS distance
FROM posts
HAVING distance <75
ORDER BY distance

This query uses the columns lat and long to return records that are within the 75 miles radius of the user.

I am not a sql expert and don't know how to merge both of the queries to gather results having the following criteria:

1. Only return posts with replies
2. Sort by their distance
3. Sort by their number of replies

Any help would be highly appreciated.

Thanks!

Answer 1

The having clause in the second query does not look correct. In most dialects of SQL is would not be allowed without a group by . I forget if MySQL t implicitly treats the whole query as an aggregation (returning one row) or if the having gets converted to a where . In either case, you should be explicit and use where when there are no aggregations.

You can just combine them by putting in the where clause. I would do it with a subquery, to make the variable definitions clearer:

      SELECT p.title, p.num, p.status, p.distance,
             COUNT( p_replies.post_num)  AS count
      FROM posts_replies pr  INNER JOIN
           (select p.*,
                   ( 3959 * acos( cos( radians( 37 ) ) * cos( radians( lat ) ) * cos( radians( lon ) - radians( -122 ) ) + sin( radians( 37 ) ) * sin( radians( lat ) ) ) ) AS distance
            from posts p
           ) p
           ON pr.post_num = p.num
      WHERE p.status = 1 AND
            p.category='uncategorized' and
            distance < 75
      GROUP BY p.num
      order by distance