Вывод даты с указанием часового и минутного смещения timezone в PostgreSQL

CREATE OR REPLACE FUNCTION date_format(date_ timestamp with time zone)
  RETURNS character varying AS
$BODY$
declare timezone_hour_ character varying;
timezone_minute_ character varying;
begin
	timezone_hour_ := (select case extract(timezone_hour from date_) 
	when 0 then extract(timezone_hour from now())::text
	else  extract(timezone_hour from date_)::text 
	end  );
	timezone_minute_ := (select case extract(timezone_minute from date_) 
	when 0 then extract(timezone_minute from now())::text
	else  extract(timezone_minute from date_)::text
	end);

	if(length(timezone_hour_) = 1) then 
		timezone_hour_ := '0' || timezone_hour_;
	end if;
	if(length(timezone_minute_) = 1) then 
		timezone_minute_ := '0' || timezone_minute_;
	end if;

	return (select to_char(date_, 'YYYY-MM-DD"T"HH24:MI:SS"+"') || timezone_hour_ || ':' || timezone_minute_);

end;$BODY$
  LANGUAGE plpgsql VOLATILE;