i will like to develop an application that allows users to buy a card and type in the PIN number and the person's account will be refilled.

i need help on this how do i implement it because if i enter the pin it overwrites the existing amount online.

how do i add the amount to the amount online.

I assume you have a problem with your update SQL when updating the user account. Check your SQL you execute when updating user account. It should be like this.

UPDATE [tablename] SET [fieldname]=[fieldname]+newamount WHERE [condition]

This will over write the current value
UPDATE [tablename] SET [fieldname]=[fieldname] WHERE [condition]



nalaka hewage