7-Day Rolling Active Users

StreamWave tracks user activity across its app and wants a daily engagement trend. Write a SQL query to calculate the 7-day rolling average of daily active users.

A user is active on a date if they generated at least one event that day.

Requirements

1. Count distinct active users per day from the user_events table. Events with a NULL user_id are anonymous and do not count toward active users.
2. Return one row for every calendar date from the earliest to the latest event date, including dates with no events. Such a date has 0 daily active users.
3. rolling_7_day_avg is the average of daily_active_users over the current date and the 6 calendar days before it. The first dates in the range have fewer than 6 earlier days, so average only the days available.
4. Round rolling_7_day_avg to 4 decimal places.
5. Return the columns event_date, daily_active_users, and rolling_7_day_avg, ordered by event_date ascending.