Function 在WHILE循环段之后从PostgreSQL函数返回行集
我正在尝试创建一个POSTGRESQL函数,该函数首先使用Function 在WHILE循环段之后从PostgreSQL函数返回行集,function,greenplum,postgresql-8.2,Function,Greenplum,Postgresql 8.2,我正在尝试创建一个POSTGRESQL函数,该函数首先使用WHILE LOOP在表中插入一些数据,然后选择该表的结果 这是一个sql示例: CREATE OR REPLACE FUNCTION get_levels_test (maxlevel int) RETURNS SETOF list_of_levels AS $$ DECLARE level int = 1; BEGIN TRUNCATE list_of_levels; WHILE (level <= maxlev
WHILE LOOP
在表中插入一些数据,然后选择该表的结果
这是一个sql示例:
CREATE OR REPLACE FUNCTION get_levels_test (maxlevel int) RETURNS SETOF list_of_levels AS $$
DECLARE
level int = 1;
BEGIN
TRUNCATE list_of_levels;
WHILE (level <= maxlevel) LOOP
INSERT INTO list_of_levels
SELECT level;
level = level + 1;
END LOOP;
select * from list_of_levels;
END;
$$ LANGUAGE PLPGSQL VOLATILE;
级别的列表只包含一个int
列
如果需要,我将使用PostgreSQL 8.2.15(Greenplum Database 4.3.3.1 build 1)。您需要使用“return next”,它可以与复合类型或表一起使用。请谨慎使用此功能,因为使用此功能可能会出现性能问题。不要使用此选项将结果连接到另一个表。不要使用此选项返回大型数据集。仅用于非常小的结果,如简短的报告
您还需要在函数中添加异常处理。我将其添加到下面的示例函数中
示例表:
create table employees
(id int not null,
manager_id int null,
employee_title text not null)
distributed by (id);
示例数据:
insert into employees values
(1, null, 'President'),
(2, 1, 'Vice-President'),
(3, 2, 'Manager'),
(4, 3, 'Engineer'),
(5, null, 'CMO'),
(6, 5, 'Director'),
(7, 6, 'Assistant'),
(8, 7, 'Developer');
功能:
create or replace function get_employees(p_id int) returns setof employees as
$$
declare
v_function_name text := 'get_employees';
v_location int;
v_rec record;
v_rec2 employees;
v_id employees.id%type;
begin
v_location := 1000;
create temporary table t1
(id integer) on commit drop distributed by (id);
v_location := 2000;
for v_rec in (select id from employees where id = p_id and manager_id is null order by id) loop
v_id := v_rec.id;
insert into t1 values (v_id);
while v_id is not null loop
select id into v_id from employees where manager_id = v_id;
if v_id is not null then
insert into t1 values (v_id);
end if;
end loop;
end loop;
v_location := 3000;
for v_rec2 in (select * from employees e join t1 on e.id = t1.id order by e.id) loop
return next v_rec2;
end loop;
exception
when others then
raise exception '(%:%:%)', v_function_name, v_location, sqlerrm;
end;
$$
language plpgsql;
以及使用该功能:
select * From get_employees(1);
id | manager_id | employee_title
----+------------+----------------
1 | | President
2 | 1 | Vice-President
3 | 2 | Manager
4 | 3 | Engineer
(4 rows)
select * From get_employees(5);
id | manager_id | employee_title
----+------------+----------------
5 | | CMO
6 | 5 | Director
7 | 6 | Assistant
8 | 7 | Developer
(4 rows)
select * From get_employees(1);
id | manager_id | employee_title
----+------------+----------------
1 | | President
2 | 1 | Vice-President
3 | 2 | Manager
4 | 3 | Engineer
(4 rows)
select * From get_employees(5);
id | manager_id | employee_title
----+------------+----------------
5 | | CMO
6 | 5 | Director
7 | 6 | Assistant
8 | 7 | Developer
(4 rows)