Discount codes

Discount codes are a great way to both entice new customers into a store, and also to help retain customers with special discounts. The discount code should work by allowing the customer to enter a code, which will then be verified by the store, and then a discount will be applied to the order.

The following are discount options we may wish to have available in our store:

• A fixed amount deducted from the cost of the order
• A fixed percentage deducted from the cost of the order
• The shipping cost altered, either to free or to a lower amount
• Product-based discounts (although we won't cover this one in the article)

It may also be useful to take into account the cost of the customer's basket; after all if we have a $5 discount code, we probably wouldn't want that to apply for orders of $5 or lower, and may wish to apply a minimum order amount.

Discount codes data

When storing discount codes in the framework, we need to store and account for:

• The voucher code itself, so that we can check that the customer is entering a valid code
• Whether the voucher code is active, as we may wish to prepare some voucher codes, but not have them usable until a certain time, or we may wish to discontinue a code
• A minimum value for the customer's basket, either as an incentive for the customer to purchase more or to prevent loss-making situations (for example a $10 discount on a $5 purchase!)
• The type of discount:
  • Percentage: To indicate that the discount amount is a percentage to be removed from the cost
  • Fixed amount deducted: To indicate that the discount amount is a fixed amount to be removed from the order total
  • Fixed amount set to shipping: To indicate that the discount amount is to be the new value for the shipping cost
• Discount amount; that is, the amount of discount to be applied
• The number of vouchers issued, if we wish to limit the number of uses of a particular voucher code
• An expiry date, so that if we wish to have the voucher code expire, codes with a date after the stored expiry date would no longer work

Discount codes database

The following table illustrates this information as database fields within a table:

The default value for num_vouchers is -1, which we will use for vouchers that are not limited to a set number of issues.

The following code represents this data in our database:

CREATE TABLE `discount_codes` (
`ID` INT( 11 ) NOT NULL AUTO_INCREMENT ,
`vouchercode` VARCHAR( 25 ) NOT NULL ,
`active` TINYINT( 1 ) NOT NULL ,
`min_basket_cost` FLOAT NOT NULL ,
`discount_operation` ENUM( '-', '%', 's' ) NOT NULL ,
`discount_amount` FLOAT NOT NULL ,
`num_vouchers` INT( 11 ) NOT NULL DEFAULT '-1',
`expiry` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP ,
PRIMARY KEY ( `ID` )
) ENGINE = INNODB DEFAULT CHARSET = latin1 AUTO_INCREMENT =1;