Entrypoint firstdaywoy compatible with UTF-8
Input TIMESTAMP date optionally time Output TIMESTAMP Date with 1st day of (US)week of the year as date with time 00:00:00
TestSQL SELECT '26.12.2004' AS ISCORRECT, F_FIRSTDAYWOY(1, 2005) FROM RDB$DATABASE;; SELECT NULL AS ISCORRECT, F_FIRSTDAYWOY(NULL) FROM RDB$DATABASE;