Saint-Gobain's commercial analytics team wants to identify the products with the highest sales volume. Using the product_sales table, write a PostgreSQL query that ranks products by the total number of units sold.
product_name and calculate total units sold with SUM.| Column | Type | Description |
|---|---|---|
| sale_idPK | INT | Unique sales record identifier |
| product_name | VARCHAR(100) | Saint-Gobain product name |
| quantity | INT | Units sold in the sales record |
| sale_date | DATE | Date of the sale |