Question

I want to write a script which will show all messages owned by ONLY users with RoleID = 4. So I tried to write something like this:

SELECT DT.DiscussionThreadID, DT.Message FROM DiscussionThread DT
INNER JOIN Users U on U.UserID = DT.CreatedBy
INNER JOIN UserRoles UR on UR.UserID = U.RoleID
WHERE UR.RoleID = 4

Example of UserRoles table:

UserID     RoleID
1          1
1          2
1          4
2          4
3          3
3          4

I expected to see only messages posted by user with UserID = 2 – he don’t have additional roles except of RoleID = 4. But my script returns all posts. Can someone help me?

Answer 1

SELECT DT.DiscussionThreadID, DT.Message
FROM DiscussionThread DT
INNER JOIN Users U on U.UserID = DT.CreatedBy
INNER JOIN UserRoles UR on UR.RoleID = U.RoleID
group by DT.DiscussionThreadID, DT.Message
having count(Distinct roleID) = 1
and max(roleID)=4