Different vendors may duplicate invoices, i.e. both vendor ABC and XYZ issue invoice number 1235. In my current position (payables processor will re-use an invoice number. Another vendor we have duplicates invoice numbers, which is a real pain. Our Payable software checks for a duplicate number against the vendor.
At the company where I was an AP supervisor, our payables module allowed duplicate numbers. Before we posted we ran the invoices through a filter (FileMaker11) that checked to see if a combined key was duplicated. The invoice number + date + amount had to be duplicated. So all of the UPS I keyed was not a duplicate because the date and amount was different. You could check this real time as you enter the invoices.
if you are entering the invoice numbers or other identifier into a field somewhere,
you can use the
List(ExampleTable::InvoiceNumberField) function to get all your invoice numbers in one field. You may need a new table occurrence of Example Table depending on how you set it up (ExampleTable|All) and use a (X) relationship.
SO from the context of ExampleTable you would have a relationship, ExampleTable::IDField X ExampleTable|All::IDField. This lets one record examine data from all records.
Next you can use the
PatternCount function like this
PatternCount(List(ExampleTable|All::InvoiceNumberField);ExampleTable::InvoiceNumber) which returns a value which is the number of times the contents of the InvoiceNumber field in the current record occurs in all records.
You could use "If" functions or "Case" functions and set up visual alerts with "Hide Object When" functionality or you could set ups a script which checks it when you commit the field using a script trigger, Perhaps you could do a calculation as a validation on the field.
Hope that is helpful,