Credit card in ASP

[pra123]

I have stored username, password, creditcard number, expiry date of card etc of my customer in ms sql database. Whenever customer makes Login, he can make some purchases.

So whenever he makes purchases, I need to deduct some amount from his
creditcard account.

For Eg: If customer purchases a book online, then I need to deduct $30 from his creditcard account.

So my Question is Wheter deducting some amount from my customer
creditcard account is a simple mathematical deduction as we do in other deductions or I need to follow some other method.

Note : creditcard types are american express, discoverer etc.

Regards.

[phpnovice]

You should not be storing credit card information in your own database. This opens you up to all kinds of additional liability problems by so doing. It is much better to require the visitor to reenter such information each time they make a purchase -- even better if they don't reenter such information on one of your own web pages (that is what credit card services are for). Be that as it may be...

No, it is not a "simple" deduction -- because, I presume, the credit card was not issued by your company and you, therefore, don't have the credit card balance information necessary to do so. Instead, you must internally submit a credit card transaction to the issuing company on which the card is based. This is normally handled by credit card services of some sort.