how to populate mysql column value based on a formula?

Question

I have created a mysql table with the following columns...

item_price, discount, delivery_charge, grand_total

The value of item_price

Answer 1

I think you'd have to use a BEFORE INSERT trigger for that:

http://dev.mysql.com/doc/refman/5.6/en/create-trigger.html

Something like this (untested off the top of my header code):

CREATE TRIGGER blahblah BEFORE INSERT ON your_table
FOR EACH ROW BEGIN
    set new.grand_total = new.item_price - new.discount + new.delivery_charge;
END;