Invoice numbers have format yymmddn
where n is sequence number in day staring at 1 for every day.
command
SELECT COALESCE(MAX(nullif(substring( substring(tasudok from 7),
'^[0-9]*'),'')::int),0)+1
FROM invoice
where date= ?invoicedate
is used to get next free invoice number if new invoice is saved.
If multiple invoices are saved concurrently from different processes, they
will probably get same number.
How to get unique invoice number for some day in 8.1+ when multiple users
create new invoices ?
Andrus.