[SOLVED] What is `AS $$` in sql functions?

What is `AS $$` in sql functions?

CREATE FUNCTION one() RETURNS integer AS $$
    SELECT 1 AS result;
$$ LANGUAGE SQL;

why i cant write like this:

CREATE FUNCTION one() RETURNS integer
    SELECT 1 AS result;

what is AS $$?
what is $$ LANGUAGE SQL?
what is $$?

Solution

In PostgreSQL it is a feature called dollar-quoting, which allows you to include a body of text without escaping the single quotes

Using it as

CREATE OR REPLACE FUNCTION hello_world(param_your_name text)
RETURNS text AS
$$
SELECT 'Hello world. My name is ' || param_your_name || '.';
$$
language sql STRICT;

which is easier to read than

CREATE OR REPLACE FUNCTION hello_world(param_your_name text)
RETURNS text AS
'
SELECT ''Hello world. My name is '' || param_your_name || ''.'';
'
language sql STRICT;