database - 带有序列的 Postgres URI 生成？

Question

所以我想在 postgres 数据库的表中创建一个列，该列自动递增一个数字并将其放在一些数据之后。又名

协议(protocol)表:

    name     |      uri      | 
_____________________________
someProtocol | /protocol/1
otherProt    | /protocol/2

有没有办法用其他数据创建某种序列？我对 postgres 列创建的了解相当有限

Answer 1

create table protocols (
  id serial primary key, -- creates a sequence int
  name text not null,
  uri text 
);

create or replace function protocols_set_uri() returns trigger as $$
begin
    new.uri = '/' || new.name || '/' || new.id; 
    return new;
end $$
language plpgsql;

create trigger protocols_set_uri 
  before insert or update on protocols 
  for each row execute procedure protocols_set_uri();

例子:

insert into protocols (name) values ('someProtocol');
select * from protocols;

结果:

id name          uri
--------------------------------
1  someProtocol  /someProtocol/1