oracle循环插入

declare
post_time number(10);
cvalue number(10,1);
begin
 post_time :=1584072610;
 cvalue := 117;
loop
post_time := post_time -20;
if post_time<1584071610 then
exit;
end if;
insert into mg_data (plc_no,para_name,machine_no,dt_post_time,DATA,pcode) values (‘s7-1200-14‘,‘双拉机热固四区风机出风温度控制‘,‘P01‘,post_time,cvalue,‘M01‘);
end loop;
end;