Usage of  Discount Coupon  depends on the pricing policy of the company. \\ 
If the pricing policy is 'free + pay per course', then the discount coupons can be used while purchasing a product.  \\ 
If the pricing policy is 'free + paid membership subscription', then the coupon can be used for the membership subscription. 

A Discount Coupon will have the following properties
Coupon code, discount,  quantity, redeemed count,  created date and  expiry date

DB schema for discount coupon

Table Name: **coupons**

^ Column_name       ^type       ^ Description   ^
| id | integer           | primary key   | 
| code | varchar           | A unique value    | 
| quantity | integer           | Number of times the coupon can be used  | 
| redeemed_count  | varchar           | number of times the coupon is used   |
| discount | varchar           | discount in percentage  | 
| expiry_date| date_time           | date on which the coupon will expire  | 
| created_at | date_time | date of which the coupon was created | 
| updated_at| date_time | coupon properties updated date |
| deleted_at| date_time | when this coupon was deleted |

Table Name: **product_coupons**

^ Column_name       ^type       ^ Description   ^
| id | integer           | primary key   | 
| coupon_id | varchar           | A unique value    | 
| product_type | integer           | type of the product. this can be 'Course', 'Certification', 'LiveEvent', or Subscription  | 
| product_id  | varchar           | On which product, this coupon can be used    |
| created_at | date_time | date of which the coupon was created | 
| updated_at| date_time | coupon properties updated date |

Table Name: **coupon_usages**

^ Column_name       ^type       ^ Description   ^
| id | integer           | primary key   | 
| user_id | integer           | id of the user who used the coupon    | 
| coupon_id | integer           | references the coupon.  | 
| product_id  | integer         | On which product, this coupon was used  |
| product_type | varchar           | type of the product, this can be 'Course', 'Certification', 'LiveEvent', or Subscription  | 
| order_id | integer | Order id |
| created_at| date_time           | date of which the coupon was created  | 
| updated_at | date_time |  |