Oracle form personalization Customer PO in Sales Order Exists or Not

Form personalization through validate the duplicate Customer PO number in Sales Order Form.

Open the oracle personalization form:

Trigger Event: WHEN-VALIDATE-RECORD

Trigger Object: ORDER

Enter the Condition:

                      (SELECT COUNT(*)  FROM oe_order_headers_all ooh
              WHERE ooh.cust_po_number = ${item.order.cust_po_number.value})>1 

Action Tab:
Message Type: Error
Message Text: Custom message