mysql where OR having

I have a table of users, some of which have articles associated with them, and some of which have type = writer. I'd like to display all users who have articles OR who have type = writer. So, all writers should be displayed, and other user types are only displayed if they have articles.

This is my query so far, which开发者_开发知识库 leaves out writers with no articles.

SELECT u.name, u.type, COUNT(a.id) count
FROM users u
LEFT JOIN articles a on u.id = a.writer_id
GROUP BY u.name
HAVING count > 0

Adding the following WHERE clause obviously excludes other user types that have articles.

WHERE u.type = 'writer'

Do I need to do a UNION of these two result sets?

I think you are looking for something like this

SELECT 
  u.name, 
  u.type, 
  COUNT(a.id) count
FROM users u
LEFT JOIN articles a ON u.id = a.writer_id
WHERE 
  u.type='writer' --all users that are writers
  OR 
  a.writer_id IS NOT NULL  --all users that have at least one article
GROUP BY 
  u.name
--removed the having clause as it seems it may be possible that a writer has no articles.

Just change the WHERE clause to allow any user that has a matching article record:

SELECT u.name, u.type, COUNT(a.id) count
FROM users u
LEFT JOIN articles a on u.id = a.writer_id
WHERE u.type = 'writer' OR a.writer_id IS NOT NULL
GROUP BY u.name
HAVING count > 0