Write a SQL query to find the top-performing promotion strategy by conversion rate, grouped by time period.
Use the provided exposure and conversion records. Treat each exposed user as one opportunity, and count a user as converted when their exposure has a matching conversion record. Return all strategies tied for the highest rate in each month.
time_period, strategy, exposed_users, converted_users, and conversion_rate.time_period ascending, then strategy ascending.| Column | Type | Description |
|---|---|---|
| exposure_idPK | INT | Unique promotion exposure identifier |
| user_id | INT | User who saw the promotion |
| strategy | VARCHAR(50) | Promotion strategy shown to the user |
| exposed_at | TIMESTAMP | Timestamp when the user saw the promotion |
| Column | Type | Description |
|---|---|---|
| conversion_idPK | INT | Unique conversion record identifier |
| exposure_id | INT | Exposure associated with the conversion |
| converted_at | TIMESTAMP | Timestamp when the conversion occurred |