System generated ASN numbers for suppliers

Summary:

Requirement to maintain ASN numbers unique across suppliers, by making use of a system generated numbering pattern.

Content (please ensure you mask any confidential information):

The business implemented supplier portal for more than 20 suppliers, who create / upload ASNs from the supplier portal, most of which have serial numbers associated with them.

As the business uses RFSMART for receiving, it becomes imperative that the ASN numbers from the suppliers are unique, to avoid discrepancies on the receiving side. Currently, Oracle does not have an option of generating a ASN number automatically.

Questions

1. How can we manage this scenario to use unique ASN numbers (ex: Supplier A will be given a numbering like A_ASN and Supplier B as B_ASN etc..)