gistfile1.txt

--App usage data are kept in the following table:

--TABLE sessions
--  id INTEGER PRIMARY KEY,
--  userId INTEGER NOT NULL,
--  duration DECIMAL NOT NULL
--Write a query that selects userId and average session duration for each user who has more than one session.
--https://www.testdome.com/questions/sql/sessions/14245?visibility=1&skillId=17

select userId, avg(duration) from sessions group by userId having count(1) > 1