PostgreSQL function for converting timestamps into OLE Dates

excel_time.sql

CREATE OR REPLACE FUNCTION excel_time(in timestamp, out double precision)
AS $$
	SELECT (EXTRACT(epoch FROM $1) / 86400) + 25569
$$
LANGUAGE SQL IMMUTABLE PARALLEL SAFE;

CREATE OR REPLACE FUNCTION excel_time(in timestamptz, out double precision)
AS $$
    SELECT (EXTRACT(epoch FROM $1) / 86400) + 25569
$$
LANGUAGE SQL IMMUTABLE PARALLEL SAFE;