Question

I have a table as follows:

User ID  Service
1        2
1        3
2        1
2        3
3        5
3        3
4        3
5        2

How could I construct a query where I would count all the user ids that have a service of 3 and at least one other service?

In the above table, the query I’m interested in would return 3 because user ids 1, 2 and 3 have service of 3 and at least one other service.

Thanks!

Answer 1

In MS SQL:

select count(*)
from UserService
where 
    ServiceId = 3 and
    UserId in (select UserId from UserService where ServiceId != 3)