> There's a boolean value indicating that the invoice is final and a numerical value for invoice number. Final invoices must have invoice numbers. But a bug in

> There's a boolean value indicating that the invoice is final and a numerical value for invoice number. Final invoices must have invoice numbers. But a bug in your system manages to update an invoice so that it's final, but missing an invoice number. Couldn't you catch that with a CHECK constraint? https://en.wikipedia.org/wiki/Check_constraint https://en.wikipedia.org/wiki/Check_constraint