In 34.4.3. SQL Functions with Output Parameters we have:
CREATE FUNCTION sum_n_product (x int, y int, OUT sum int, OUT product
int) AS
'SELECT $1 + $2, $1 * $2'
LANGUAGE SQL;
SELECT * FROM sum_n_product(11,42);
sum | product
-----+---------
53 | 462
(1 row)
Then in 34.4.7. SQL Functions Returning Sets we have (without
an example SELECT statement):
CREATE FUNCTION sum_n_product_with_tab (x int, OUT sum int, OUT
product int) RETURNS SETOF record AS $$
SELECT $1 + tab.y, $1 * tab.y FROM tab;
$$ LANGUAGE SQL;
The problem is that if the reader copies and pastes the last function
definition and then attempts to run it, quite obviously he gets an
error because there is no table "tab".
I would add a table definition and fill it with dummy data and then
give two example SELECT statements after the function definition:
CREATE TABLE tab ( y integer, z integer );
INSERT INTO tab VALUES (1, 2), (3,4), (5,6), (7,8);
CREATE FUNCTION sum_n_product_with_tab (x int, OUT sum int, OUT
product int) RETURNS SETOF record AS $$
SELECT $1 + tab.y, $1 * tab.y FROM tab;
$$ LANGUAGE SQL;
SELECT sum_n_product_with_tab(10);
SELECT * from sum_n_product_with_tab(10);
I think one of the things this presentation accomplishes is to
emphasize that a table definition is really not much more than a type
definition or object definition or what you will. That is not said
derogatorily at all. Rather, I believe it emphasizes the
extraordinary power of Postgresql.
John
