How do I reference named parameters in Postgres sql functions?

Question

Postgres noobie here.

I\'m trying to convert a SQL Server stored proc into a Postgres function. Currently cannot figure out how to turn this SQL line into Postgres.

Answer 1

You cannot use named parameters in a function that is defined with language=SQL.

You need to use the the placeholder $1.

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($1, u.name);

$$
LANGUAGE sql;

This behaviour is documented in the manual: http://www.postgresql.org/docs/9.0/static/xfunc-sql.html

So far as the SQL function itself is concerned, these names are just decoration; you must still refer to the parameters as $1, $2, etc within the function body

Edit

Since version 9.2 it is possible to use named parameters with (plain) SQL function
http://www.postgresql.org/docs/9.2/static/xfunc-sql.html#XFUNC-SQL-FUNCTION-ARGUMENTS