>Currently we have a database file having details of books.
>
>One of the fields is the ISBN Number which is to be converted to barcode format.
>

Typically, the barcode on the jacket adheres to EAN13, prefixes with '78', followed by the most significant 9 characters of the ISBN (drop the check digit) with a unit of measure postfix. If you just want to produce a random barcode for in-house use, 3 of 9 is a common and well-supported format.