Below is Simple Query to get Query to get UNPAID Invoices (Oracle Payables). I have alos build condition to exclude ZERO Dollar Invoices.
FROM ap_payment_schedules_all ps,
WHERE i.invoice_id = ps.invoice_id
AND i.vendor_id = v.vendor_id
AND i.vendor_site_id = vs.vendor_site_id
AND i.payment_status_flag ='N'
AND (nvl(ps.amount_remaining, 0) * nvl(i.exchange_rate,1)) != 0
AND i.cancelled_date is not null
group by v.vendor_name,i.invoice_num,i.invoice_date,ps.due_date,i.invoice_amount,i.amount_paid,
Order by v.vendor_name,i.invoice_num
Special Thanks to Kunal for suggesting "i.cancelled_date is not null" , with this new condition Query will not reterive Cancelled Invoices" from database.