Hi

There is no need to write pl/sql code at all...

1)create a table called sop-t table
2)load the records into this table
3)write your insert statement as follows
insert into sop_employee
select department_name,subdepartment_name ,employee_id from sop_employee
minus
select department_name,subdepartment_name ,employee_id from sop-t

truncate sop-t table and then later drop it..

regards
Hrishy