SELECT COUNT(*) FROM(SELECT distinct ra.emp_id FROM EMPLOYEE ra WHERE  
ra.emp_id in
  (
  select rs.emp_id from employee_details rs WHERE rs.chg_date = '20080218' And 
  (rs.status in('ab','ac')
   OR (ra.dept_id in ('S','L')and rs.status ='E') 
  )
  ) 
  OR  ra.request_id IN 
  (
  SELECT r.emp_id from employee r  where TRUNC(r.CHG_DATE) = TO_DATE('18/02/2008','DD/MM/YYYY') 
  And (r.status in('ab','ac')
   OR (ra.dept_id in ('S','L')and r.status ='E') 
  ) 
  ) 
)