You can add more conditions to your JOIN using AND. I did part of the job here. You need to work on the rest.
SELECT Projects, Hours
FROM Projects
LEFT JOIN ProjTime
ON Projects.Group=ProjTime.Group
AND Projects.Project=ProjTime.Project;
Luis C.
General Disclaimer:
Are you seriously taking the advice and code from someone from the internet without testing it? Do you at least understand it? Or can it easily kill your server?
How to post data/code on a forum to get the best help: Option 1 / Option 2