SQL conditions for checkout proccess

[Richard Russo <richardr@dgx.net>]

Is it possible to check the results of an SQL query based (to some
degree) on user input from the checkout form, before proccessing
payment?

For example, if there is a guarantee of 2 day delivery on an item, but
the item is no longer in stock, it could check a database to see if
there is sufficent product left to ship the order.

Richard Russo
DGX InterNET