SELECT Nameemployee, AVG(Cost)
FROM Department o, Staff s,Promotions y, ComponentsPromotions p
WHERE  o.IdDepartment =s.IdDepartment and s.IdStaff=y.IdStaff and y.IdPromotion=p.IdPromotion
GROUP BY Nameemployee
HAVING AVG(Cost) >(SELECT o1.IdDepartment ,AVG(Cost)
FROM Department o1, Staff s1,Promotions y1, ComponentsPromotions p1
WHERE  o1.IdDepartment =s1.IdDepartment and s1.IdStaff=y1.IdStaff and y1.IdPromotion=p1.IdPromotion
GROUP BY o1.IdDepartment)