PostgreSQL 的 分布函数 cume_dist
create table a7(id integer, value integer);
insert into a7 values(1,100);
insert into a7 values(2,200);
insert into a7 values(3,300);
insert into a7 values(4,400);
insert into a7 values(5,500);
select id, value, cume_dist() over (order by id) as percent from a7;
1 100 0.2
2 200 0.4
3 300 0.6
4 400 0.8
5 500 1