Generating sequential numbers in multi-user saas application

Question

How do people generate auto_incrementing integers for a particular user in a typical saas application?

For example, the invoice numbers for all the invoices for a partic

Answer 1

Not sure if this is the best solution, but you could store the last Invoice ID on the User and then use that to determine the next ID when creating a new Invoice for that User. But this simple solution may have problems with integrity, will need to be careful.