You need a database with a column called for example 'itemAvailable'
which contains a single character; a 0 or a 1 to indicate the status of the
availability of each item; 0 = not available, 1 = available. Of course using
string characters T(rue) and F(alse) could also be used.
The database is accessed every time a shopper views a page for that item.
If the value of itemAvailable is 1 then nothing extraordinary needs to be
displayed but if the value of itemAvailable is 0 the output of the page is
modified to inform the shopper that the item is currently not available.
Each time an available item is sold the value of itemAvailable for that
item is changed to 0.
Savvy merchants also include a method to ask the shopper if they would
like to receive e-mail informing the customer that the item is available
again. It is also not unheard of to enable the customer to remit a fee to
put an item on hold, when the item is once again available the customer
is notified via e-mail, returns to the merchant's site and finishes the
transaction. Finally, the merchant needs page(s) to manage the entire
process.
I've developed many e-commerce business processes and use either ASP
or ASP.NET with IIS should you need professional assistance...
