Postgresql 函数在表中插入多行

因此，我有以下表格

             G
__________________________
id_musician  |    id_album
--------------------------
1            |    51
3            |    52
2            |    53
3            |    54
1            |    55
3            |    56

            C
__________________________
id_album    |      year
--------------------------
51          |    1990
52          |    2001
53          |    1990
54          |    2001
55          |    1945
56          |    1945

我创建了以下函数：

CREATE OR REPLACE FUNCTION test2 (year1 INTEGER, p_type VARCHAR(1))
RETURNS SETOF test2 AS $$
DECLARE
output test2;
BEGIN
IF p_type='S' THEN
FOR output IN SELECT g.id_artist, c.year, COUNT(c.id_album) AS albums
FROM G g, C c
WHERE g.id_album = c.id_album AND
c.year = year1
GROUP BY c.year, g.id_musician
LOOP
RETURN NEXT output;
END LOOP;
END IF
RETURN;
END;
$$LANGUAGE plpgsql;

CREATE OR REPLACE FUNCTION test2 (year1 INTEGER, p_type VARCHAR(1))
    RETURNS SETOF test2 AS
$BODY$
BEGIN
    IF p_type='S' THEN
        RETURN QUERY (
            WITH inserted AS (
                INSERT INTO test2_table
                SELECT g.id_musician, c.year, COUNT(c.id_album)::INTEGER AS albums
                FROM g, c
                WHERE g.id_album = c.id_album
                AND c.year = year1
                GROUP BY c.year, g.id_musician
                RETURNING *
            )
            SELECT *
            FROM inserted
        );
    ELSE
        RETURN;
    END IF;
END
$BODY$
    LANGUAGE plpgsql;

test2是我创建的一种输出类型：

CREATE TYPE test2 AS(
        id smallint,
        year smallint,
        total_albums integer)

该函数接受一年和一种performer。它返回，对于每一年和表演者（在本例中是吉他手“G”），表演者每年参与的唱片数量

我希望函数将该输出插入到我创建的表中，而不仅仅是显示输出：

CREATE TABLE TEST2_TABLE (
id smallint,
year smallint,
total_albums integer );

下面是函数：

CREATE OR REPLACE FUNCTION test2 (year1 INTEGER, p_type VARCHAR(1))
RETURNS SETOF test2 AS $$
DECLARE
output test2;
BEGIN
IF p_type='S' THEN
FOR output IN SELECT g.id_artist, c.year, COUNT(c.id_album) AS albums
FROM G g, C c
WHERE g.id_album = c.id_album AND
c.year = year1
GROUP BY c.year, g.id_musician
LOOP
RETURN NEXT output;
END LOOP;
END IF
RETURN;
END;
$$LANGUAGE plpgsql;

CREATE OR REPLACE FUNCTION test2 (year1 INTEGER, p_type VARCHAR(1))
    RETURNS SETOF test2 AS
$BODY$
BEGIN
    IF p_type='S' THEN
        RETURN QUERY (
            WITH inserted AS (
                INSERT INTO test2_table
                SELECT g.id_musician, c.year, COUNT(c.id_album)::INTEGER AS albums
                FROM g, c
                WHERE g.id_album = c.id_album
                AND c.year = year1
                GROUP BY c.year, g.id_musician
                RETURNING *
            )
            SELECT *
            FROM inserted
        );
    ELSE
        RETURN;
    END IF;
END
$BODY$
    LANGUAGE plpgsql;

因此，签名和输出与原始函数相同。主要区别是：

• 无需使用循环并一次读取/返回一行。您可以直接返回查询结果。像那样快得多
• 为了完成插入到表中和返回相同的结果，它使用一个CTE将数据插入表中并返回插入的所有内容，然后从该CTE中选择作为返回输出

---

我还删除了别名。postgres中的任何标识符都是小写的，除非使用双引号。由于

G

和

C

不在引号中，因此表名实际上分别是

G

和

C

。因此，我只使用了实际的小写表名。

“将该输出插入到我创建的表中”，您没有向我们显示该表，而是重新发布了类型定义。那么您希望它将输出写入表并返回它，还是只是写入它？对不起，这是一个错误，我现在已经更正了。该表为空，理想情况下，它将返回类型并将其插入到表TEST2\u表中。然而，如果这不可能，我会满足于只填充表格的函数