-- https://docs.oracle.com/en/database/oracle/oracle-database/23/sqlrf/JSON_TABLE.html
SELECT requestor, has_zip
FROM j_purchaseorder,
JSON_TABLE(po_document, '$'
COLUMNS
  (requestor VARCHAR2(32) PATH '$.Requestor',
   has_zip VARCHAR2(5) EXISTS PATH '$.ShippingInstructions.Address.zipCode'));