Oracle 11g Release 2

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CREATE TABLE identity_invoice_info_cfv ( COMPANY, IDENTITY, CF$_DELIVERY_TYPE, PARTY_TYPE_DB ) AS
SELECT 'A', 123, 456, 'CUSTOMER' FROM DUAL;
1 rows affected

CREATE TABLE tax_ledger_item_tab ( identity, company, party_type, delivery_type_id, fetched ) AS
SELECT 123, 'A', 'CUSTOMER', CAST( NULL AS NUMBER ), 'FALSE' FROM DUAL;
1 rows affected

MERGE INTO tax_ledger_item_tab t
USING identity_invoice_info_cfv i
ON (
    t.identity      = i.identity
AND t.company       = i.COMPANY
AND t.party_type    = 'CUSTOMER'
AND i.PARTY_TYPE_DB = 'CUSTOMER'
)
WHEN MATCHED THEN
  UPDATE
  SET delivery_type_id = i.CF$_DELIVERY_TYPE,
      fetched          = 'TRUE'
  WHERE t.delivery_type_id IS NULL;
1 rows affected

SELECT * FROM tax_ledger_item_tab;


IDENTITY
COMPANY
PARTY_TYPE
DELIVERY_TYPE_ID
FETCHED


123
A
CUSTOMER
456
TRUE