>>I think I will follow McCalland sugestion to recall the deleted record, because the PK is my invoice-number (The invoicenr. should be unique and it should be a numeric sequential number [1,2,3,4,5,6] or else the IRS will complain.)
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>If that is the case, why was the record deleted in the first place? Was the invoice voided? In such case, our IRS would be most upset if we voided an invoice then re-used the invoice number for a different/new sale or transaction. By recalling the deleted record or re-using an invoice number, we would in effect be erasing the electronic paper trail the IRS requires of our businesses.

The user can delete an invoice when he hasn't send the invoices to the client but already printed the invoice. If he then finds out that he has forgotten something, he can delete the invoice reset the invoice-counter and recreate the invoice with the same number?

Maybe I can do the following :
Before I delete the invoice I can relpace the invoicenr with sys(3).
after this the original number is available .
Should this strategy get me into problems ?