Write a SQL query using window functions to rank users by transaction volume.
Use total transaction amount as the volume measure and include users without transactions.
user_id, username, total_volume, and volume_rankvolume_rank ascending, then user_id ascending| Column | Type | Description |
|---|---|---|
| user_idPK | INT | Unique user identifier |
| username | VARCHAR(100) | User display name |
| Column | Type | Description |
|---|---|---|
| transaction_idPK | INT | Unique transaction identifier |
| user_id | INT | User associated with the transaction |
| amount | NUMERIC(12,2) | Transaction amount |