Mysql Find users that are part of two differnt projects

Question

I'm searching my submission fields for users that signed up for two different projects. This is what I have, that is not working correctly. Any help would be great!

SELECT 
    user_id, COUNT(*) 
FROM submissions 
WHERE 
    project_id = 125 
    or project_id = 81 
group by 
    user_id 
HAVING COUNT(*) >= 2

So to clarify, I want to know what users have a submission from project_id 81 AND project_id 125. Each of the submissions

Answer 1

The right sintax is this one, you're missing a *

SELECT
  user_id, COUNT(*)
FROM
 submissions
WHERE
 project_id = 125 or project_id = 81
GROUP BY
  user_id
HAVING
  COUNT(*) >= 2

in case a user can submit the same project multiple times, it's better to write your HAVING condition like this:

HAVING COUNT(DISTINCT project_id)>=2

so we can be sure that it will match two different distinct projects, and not just one project submitted multiple times