Discount calculation [closed]

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Closed 8 years ago.

I'm currently designing a database for my company's website. I would like to create a table which will hold information (logic) about our discounts so that I can just call a function with a discountID and my php code will calculate the new price. My question is, every discount has different logic. ex. 10% off, $10 off, by one get one free, buy 3 get 50% off...

How can I store this in the database so that my code can calculate the discount on its own?

Answer 1

A database does not store logic - only data. Split this into three fields:

• discount amount (int)
• discount type (enum; possible values: 'percent', 'amount')
• buy one get N free (int; the number you get free for every one bought)

So for one discount you might store the following:

| discount amount | discount type | buy one get one free |
----------------------------------------------------------
|       10        |   'percent'   |                      |

For another, where BOGOF applies:

| discount amount | discount type | buy one get N free |
----------------------------------------------------------
|                 |               |         1          |

Then it would be up to your PHP to receive these values and act accordingly.

Answer 2

You must to create discount table with such fields for example:

1. discount_id - ID of the discount
2. percent - % of discount (if 0 - then it's discount of other type)
3. amount - amount of discount in $ (if 0 - then it's discount of other type)
4. items - number of free items when buy something (one get - one free in your example)
5. bought_items - condition, in what case you give a discount (if 0 - no conditions)

Or you can give other names to the fields. According to values you may know what type of discount and what condition to give it.

Answer 3

This is where I would normally start with a multi-tiered approach, since it not only will be for calculating but may be used to show on the actual website. I would start with two tables.

Promotion Table
| id | discount_type | qty_products | discount_amount | free_products |
-----------------------------------------------------------------------
|  1 | BOGO          |       2      |        0        |       1       |


Sales Promo
| id | promo_id | product_id | activation_date | expiration_date |
------------------------------------------------------------------
|  1 |     1    |     222    |   '2012-04-23'  |   '2012-05-12'  |

Then the code would look to see if it was in date range and apply the discount or B1G1/B1G2. Tables are not exact but a start.