没有依赖项递归表的查询

Question

我正在尝试选择一个没有依赖关系的数据库注册表（请看图中和结果）。

结果

我尝试了以下功能：

create or replace function consultar(id integer)
RETURNS TABLE(cod character varying, nom character varying) as
$$
declare
ids character varying[];
begin
ids:=(select array(select distinct tb_plan_p from 
tb_plan where 
tb_plan_p is not null order by tb_plane_p));

RETURN QUERY
select tb_plan_cod, tb_plan_des
from tb_plan
where tb_plan_cod <> any(ids) order by tb_plane_cod;
end;
$$ LANGUAGE plpgsql;

我首先尝试创建一个包含有依赖项的cod的数组，然后从结果中删除那些cod 但是我没有想要的东西

Answer 1

我不能完全确定我已正确理解该要求，但在我看来，您正在寻找此查询：

SELECT cod, name
FROM tb_plan AS p1
WHERE fk IS NOT NULL
  AND NOT EXISTS (
         SELECT 1
         FROM tb_plan AS p2
         WHERE p2.fk = p1.cod
      );