PROCEDURE SALARY_DIFF
   IS
cursor bonus_salary is
  SELECT
      first_name,
      last_name,
      salary
    FROM bonus
      order by salary desc;

type bonus_salary_rec_type is record (
  first_name bonus.last_name%TYPE,      
  last_name  bonus.last_name%TYPE,
  salary     bonus.salary%TYPE);

bonus_salary_rec bonus_salary_rec_type; 
  
v_diff       bonus.salary%TYPE;      
v_old        bonus.salary%TYPE;            

BEGIN
open bonus_salary;
   select max(salary) into v_old from bonus;
   loop
     fetch bonus_salary into bonus_salary_rec;
     exit when bonus_salary%notfound;
     v_diff := bonus_salary_rec.salary - v_old;
     -- dbms_output.put_line(v_last_name||' '||v_salary||' '||v_diff);
     v_old := bonus_salary_rec.salary;
     update bonus set difference = v_diff where
       first_name = bonus_salary_rec.first_name and
       last_name  = bonus_salary_rec.last_name; 
     
   end loop;
close bonus_salary;
     
END; -- Procedure

Gehaltsunterschied mit reinem Oracle-SQL

select last_name, salary, prior salary-salary  from (
select rownum rn , rownum-1 rnm, last_name, salary from (
  select last_name, salary from employees order by salary desc)
) connect by prior rn = rnm