
Are you trying to find the link between customer invoice and delivery note?
This SQL query will show you how
select b.PACKINGSLIPID packingSlip, c.invoiceId invoiceid, QUANTITY
from CUSTINVOICEPACKINGSLIPQUANTITYMATCH a
join CUSTPACKINGSLIPTRANS b
on a.PACKINGSLIPSOURCEDOCUMENTLINE = b.SOURCEDOCUMENTLINE
join CUSTINVOICETRANS c
on a.INVOICESOURCEDOCUMENTLINE = c.SOURCEDOCUMENTLINE