Question

I’ve looked around for an answer to this but I’m not finding it. I have a site with articles stored in an article table and writers in the user table. I wanted to get a list of authors ordered by how recently they’d written an article.

This gives me the User ids:

SELECT distinct a.user_id 
FROM `article` as a 
ORDER BY a.id desc

The problem is that as soon as I try to bring the names in by joining the order changes so that it’s by user id. I’ve tried this:

SELECT distinct a.user_id, u.name 
FROM `article` as a 
LEFT JOIN user as u on u.id  = a.user_id 
ORDER BY a.id desc, u.id desc

and

SELECT distinct a.user_id, u.name 
FROM `article` as a 
LEFT JOIN user as u on u.id  = a.user_id 
ORDER BY u.id desc, a.id desc

but both alter the order of the names. I’m obviously doing something stupid, but what?

Answer 1

The fact that DISTINCT happens to work with ORDER BY in your first example is a fluke, and not standard SQL. You need something like this:

SELECT a.user_id, u.name 
  FROM article a 
  LEFT JOIN user u ON u.id = a.user_id 
  GROUP BY a.user_id
  ORDER BY MAX(a.id) desc