MySQL order by before group by

Question

There are plenty of similar questions to be found on here but I don\'t think that any answer the question adequately.

I\'ll continue from the current most popular qu

Answer 1

** Sub queries may have a bad impact on performance when used with large datasets **

Original query

SELECT wp_posts.*
FROM   wp_posts
WHERE  wp_posts.post_status = 'publish'
       AND wp_posts.post_type = 'post'
GROUP  BY wp_posts.post_author
ORDER  BY wp_posts.post_date DESC; 

Modified query

SELECT p.post_status,
       p.post_type,
       Max(p.post_date),
       p.post_author
FROM   wp_posts P
WHERE  p.post_status = "publish"
       AND p.post_type = "post"
GROUP  BY p.post_author
ORDER  BY p.post_date; 

becasue i'm using max in the select clause ==> max(p.post_date) it is possible to avoid sub select queries and order by the max column after the group by.