Combining two queries into one query if possible

Question

Hi there. I would like, if possible, to somehow combine the queries 1) and 2) into a single query.
1) select distinct user_id from system_user_sessions;
This query returns all unique users from the indicated table.
2) select count(session_id) from system_user_sessions where user_id = "each user_id returned from 1)";
This query will return, for each distinct user_id, the number of sessions involving that user. In other words I would like to return the user_id of each user together with the number of session_ids involving that user.
any ideas? Joe

Answer 1

I assume you are looking for something like this:
select count(session_id)
  from system_user_sessions
where user_id in ( select distinct user_id
                      from system_user_sessions
                  );HTH
Ghulam