Table: purchases

+--------------+---------+
| Column Name  | Type    |
+--------------+---------+
| order_id     | integer |
| user_id      | integer |
| product_type | varchar |
| quantity     | integer |
| order_date   | date    |
+--------------+---------+

order_id is the primary key for this table.
Each row represents one purchase transaction. quantity indicates the number of items purchased in that transaction.