DoorDash wants a city-level view of the merchants generating the most revenue. Write a PostgreSQL query using data through 2026-08-29 to find the top three merchants by delivered order revenue in each city during the previous 30 days, from 2026-07-31 through 2026-08-29 inclusive.
status = 'delivered' and order_total values from the 30-day period.merchant_id, and return ranks 1 through 3.| Column | Type | Description |
|---|---|---|
| city_idPK | INT | Unique city identifier |
| city_name | VARCHAR(100) | DoorDash market name |
| Column | Type | Description |
|---|---|---|
| merchant_idPK | INT | Unique merchant identifier |
| merchant_name | VARCHAR(150) | Merchant display name |
| city_id | INT | City where the merchant operates |
| Column | Type | Description |
|---|---|---|
| order_idPK | INT | Unique order identifier |
| merchant_id | INT | Merchant associated with the order |
| order_total | NUMERIC(10,2) | Revenue attributed to the order |
| placed_at | TIMESTAMP | Timestamp when the order was placed |
| status | VARCHAR(20) | Order lifecycle status |