Question

This is my query:

Select COUNT(*) 
From 
    Users u
    Inner Join 
    UsersLoginHistory uh On u.UserID = uh.UserID 
Where 
    1 = 1   
    And 
    u.AccountID = 37 
Group By u.UserID

What I’d like to be able to get is Count(*) should be returning a number after grouping on u.UserId. But it returns the Count(*) before the group by is made.

So I can rewrite the above query as:

Select COUNT(*)
From (
    Select   u.Username   
    From 
        Users u
        Inner Join 
        UsersLoginHistory uh On u.UserID = uh.UserID 
    Where 
        1 = 1   
        And 
        u.AccountID = 37 
    Group By u.UserID
) v

But I need to find out why is the Count(*) returning records before a group by is made and how can I fix the 1st query itself.

EDIT: Sample Records

Users table

UserId     Username
102        tom.kaufmann

UserLoginHistory table

UsersLoginHistoryID UserID  LoginDateTime         LogoutDateTime         IPAddress
1                    102    2012-09-28 01:16:00 NULL                 115.118.71.248
2                    102    2012-09-28 01:29:00 2012-09-28 01:29:00  127.0.0.1
3                    102    2012-09-28 01:32:00 2012-09-28 01:32:00  127.0.0.1
4                    102    2012-09-28 01:41:00 NULL                 115.118.71.248
5                    102    2012-09-28 01:43:00 2012-09-28 07:04:00  115.118.71.248  

and so on..

Haven’t writted every single record in this DB.

Answer 1

Based on your second query which you say returns the desired results (and assuming UserID is the PK of Users) I presume this is what you need

SELECT Count(UserID)
FROM   Users u
WHERE  u.AccountID = 37
       AND EXISTS (SELECT *
                   FROM   UsersLoginHistory uh
                   WHERE  u.UserID = uh.UserID)

This will be more efficient than expanding out all the joined rows then collapsing them again with Group By u.UserID and counting the number of rows that result.