Postgres function using returns

psql-returns.sql

CREATE OR REPLACE FUNCTION public.fn_subscriber_save(
    IN _emailaddress character varying,
    IN _firstname character varying,
    IN _lastname character varying,
    IN _subscribeurl character varying,
    IN _mobilenumber character varying DEFAULT NULL::character varying,
    IN _ipaddress cidr DEFAULT NULL::cidr)
  RETURNS TABLE(subscriberid integer) AS
$BODY$
DECLARE
  __email_emailid     integer;
  __identity_emailid  integer;
  __identity_subscriberid   integer;
BEGIN  
  __identity_subscriberid = 0;

  -- lets see if there is already an email in database
  SELECT emailid INTO __email_emailid
    FROM email
    WHERE emailaddress = _emailaddress;

  -- insert email if it does not already exists
  -- else update subscriber info
  IF __email_emailid IS NULL THEN
  
    INSERT INTO email(emailaddress)
      VALUES(_emailaddress)
      RETURNING emailid INTO __identity_emailid;
      
    INSERT INTO subscriber(emailid, firstname, lastname, subscribeurl, ipaddress, mobilenumber)
      VALUES(__identity_emailid, _firstname, _lastname, _subscribeurl, _ipaddress, _mobilenumber)
      RETURNING subscriber.subscriberid INTO __identity_subscriberid;
      
  ELSE
  
    IF _mobilenumber IS NOT NULL THEN
      UPDATE subscriber SET
        mobilenumber = _mobilenumber,
        dateupdated = (now() at time zone 'utc')
      WHERE emailid = __email_emailid;
    END IF;
    
    IF _firstname <> '' THEN
      UPDATE subscriber SET 
        firstname    = _firstname,
        dateupdated = (now() at time zone 'utc')
      WHERE emailid = __email_emailid;
    END IF;
    
    IF _lastname <> '' THEN
      UPDATE subscriber SET 
        lastname     = _lastname,
        dateupdated = (now() at time zone 'utc')
      WHERE emailid = __email_emailid;
    END IF;
  SELECT s.subscriberid INTO __identity_subscriberid
    FROM subscriber s
    JOIN email e on e.emailid=s.emailid
    WHERE e.emailaddress=_emailaddress;
    
END IF;

RETURN QUERY SELECT __identity_subscriberid as subscriberid;
  
END
$BODY$
  LANGUAGE plpgsql VOLATILE