相关疑难解决方法(0)

返回TABLEvs 的函数和SETOF records其他所有函数之间的区别是什么.

CREATE FUNCTION events_by_type_1(text) RETURNS TABLE(id bigint, name text) AS $$
    SELECT id, name FROM events WHERE type = $1;
$$ LANGUAGE SQL STABLE;

CREATE FUNCTION events_by_type_2(text) RETURNS SETOF record AS $$
    SELECT id, name FROM events WHERE type = $1;
$$ LANGUAGE SQL STABLE;

这些函数似乎返回相同的结果.看到这个SQLFiddle.

Postgres noobie在这里.

我正在尝试将SQL Server存储过程转换为Postgres函数.目前无法弄清楚如何将此SQL行转换为Postgres.

SQL Server:

input: @name = null

SELECT *
FROM table
WHERE name = ISNULL(@name, name)

Postgres的:

input: n = null

SELECT *
FROM table
WHERE name = COALESCE(n, name)

我收到错误"列n不存在".如何在Postgres函数的select语句中引用参数？

更新:

Postgres函数的定义

CREATE OR REPLACE FUNCTION fn_name (n VARCHAR(32) = NULL, name OUT varchar(32), description OUT varchar(64))
RETURNS setof record
AS 
$$
    SELECT u.name
        , u.description
    FROM table_a u
    WHERE u.name = COALESCE(n, u.name);

$$
LANGUAGE sql;