Error in update statement - response (3) by Raja_KT

Maybe you can dont you try with merge into statement?
 
similar to
 
MERGE INTO Department
      USING USING (SELECT .......

FROM contact
WHERE contact_number = ....)  a
on (condition a=b)
WHEN MATCHED THEN UPDATE
      SET budget_amount = nd.Budget_Amount
WHEN NOT MATCHED THEN INSERT
VALUES
(....);
you can remove the insert part if not needed.
Cheers,
Raja