| product_id | product_name | unit_price | | ---------- | ------------ | ---------- | | 1 | S8 | 1000 | | 2 | G4 | 800 | | 3 | iPhone | 1400 |

| seller_id | product_id | buyer_id | sale_date | quantity | price | | --------- | ---------- | -------- | ---------- | -------- | ----- | | 1 | 1 | 1 | 2019-01-21 | 2 | 2000 | | 1 | 2 | 2 | 2019-02-17 | 1 | 800 | | 2 | 2 | 3 | 2019-06-02 | 1 | 800 | | 3 | 3 | 4 | 2019-05-13 | 2 | 2800 |