PostgreSQL函式：返回表查詢結果集

一、建立測試表
create table jason01.jason123(aa varchar);
insert into jason01.jason123 values('aa');
insert into jason01.jason123 values('ab');
insert into jason01.jason123 values('bb');

postgres=# select * from jason01.jason123;
 aa
----
 aa
 ab
 bb
(3 rows)

二、建立函式

1、方法一：使用%rowtype
CREATE OR REPLACE FUNCTION jason01.fun_resultset() RETURNS SETOF jason01.jason123 AS
$$
DECLARE
    r jason01. jason123%rowtype ;
BEGIN
    FOR r IN SELECT * FROM jason01.jason123 where aa like 'a%'
    LOOP
        RETURN NEXT r;
    END LOOP;
    RETURN;
END
$$ LANGUAGE plpgsql;

postgres=# select jason01.fun_resultset();
 fun_resultset
---------------
 (aa)
 (ab)
(2 rows)

2、方法二：使用record型別
CREATE OR REPLACE FUNCTION jason01.fun_resultset1() RETURNS SETOF jason01.jason123 AS
$$
DECLARE
    r record;
BEGIN
    FOR r IN SELECT * FROM jason01.jason123 where aa like 'b%'
    LOOP
        RETURN NEXT r;
    END LOOP;
    RETURN;
END
$$ LANGUAGE plpgsql;

postgres=# select jason01.fun_resultset1();
 fun_resultset1
----------------
 (bb)
(1 row)

3、方法三：使用cursor + record
CREATE OR REPLACE FUNCTION jason01.fun_resultset2() RETURNS SETOF jason01.jason123 AS
$$
DECLARE
    C CURSOR FOR SELECT * FROM jason01.jason123 where aa like 'a%';
    R RECORD;
BEGIN
    FOR r IN C
    LOOP
        RETURN NEXT r;
    END LOOP;
    RETURN;
END
$$ LANGUAGE plpgsql;

postgres=# select jason01.fun_resultset2();
 fun_resultset2
----------------
 (aa)
 (ab)
(2 rows)