CREATE OR REPLACE PROCEDURE prc_pm_cpu(in_portid integer,
                                       in_stime  date,
                                       in_etime  date) is
  v_value number;
  v_mincpuused number;
  v_maxcpuused number;
begin
  begin
    select t.cpuused
      into v_mincpuused
      from s_pm_cpu t
     where t.portid = in_portid and t.starttime=in_stime;
     
    select t.cpuused 
      into v_maxcpuused
      from s_pm_cpu t
     where t.portid = in_portid and t.starttime=in_etime;
     
 v_value:=v_maxcpuused-v_mincpuused;
 
  end;
  commit;
end prc_pm_cpu;