SQL · Meta · Hard
You are handed a small call-tracking database with three relations. All timestamps are UTC and are given as YYYY-MM-DD HH24:MI:SS. calls(call_id INT PRIMARY KEY, host_user_id INT, start_ts TIMESTAMP, end_ts TIMESTAMP, is_group_enabled BOOLEAN) call_participants(call_id INT, user_id INT, join_ts TIMESTAMP, leave_ts TIMESTAMP) — leave_ts is NULL when the attendee is still present when the call finishes users(user_id INT PRIMARY KEY, email TEXT, country TEXT, is_test BOOLEAN)…
Checking your access…