Here is the perform logic for preventing AP invoice records from import. This checks the invoice history file for existing invoices (Div+VendorNo+InvoiceNo) and was developed by Alnoor Cassim for v4.30 but still works for 2017.

Step 1: copy the text below into notepad and save the file as "AP_VISkipDuplicateInvoices.m4p"

Step2: place file AP_SkipDuplicateInvoices.m4p into the AP directory

Step3: add VI perform logic as follows:

   JobName: (whatever your VI job name is)

   Perform Type: Before Assign

   File Type: Header

   Table Name: AP_InvoiceHeader

   Column Name: InvoiceNo

   Sequence: 001

   Command:  ..\AP\AP_VISkipDuplicateInvoices.m4p;ENTRY_POINT

----- copy the text below into notepad and name the file AP_VISkipDuplicateInvoices.m4p --------

! In V/I Import Job set the PERFORM to run on 
! BEFORE ASSIGN of Header on table AP_InvoiceHeader column InvoiceNo
! Command = ..\AP\AP_VISkipDuplicateInvoices.m4p;ENTRY_POINT

ENTRY_POINT:
IF NOT(coInvcHistHdr) THEN {
coInvcHistHdr = NEW("AP_InvoiceHistoryHeader_Svc",%SYS_SS)
}

InvoiceNo$ = VAR$

retExists =coInvcHistHdr'CheckInvoiceHistory(APDivisionNo$, VendorNo$, InvoiceNo$)

IF retExists THEN { VAR$=$$ }

EXIT