SQL Weekly Retention After First Ride

Didi Chuxing's Product Growth team wants to evaluate how consistently new riders return after completing their first ride. Given a target month, calculate weekly retention for users whose first completed ride occurred during that month.

Use January 2025 as the target month for the supplied data. A retention week is the number of calendar weeks elapsed since the user's cohort week, where weeks begin on Monday. Count a user once per retention week even if they complete multiple rides during that week.

Output

1. One row per cohort week and retention week, including retention week zero through the latest observed retention week.
2. Columns: cohort_week, retention_week, retained_users, cohort_users, and retention_rate.
3. Include users only when their first completed ride is in the target month. Include zero-retention weeks for each cohort, and sort by cohort_week, then retention_week ascending.