ORACLE判断两个日期间隔几个工作日

/**
 * 判断两个日期间隔几个工作日
 */
CREATE OR REPLACE FUNCTION "FUN_BETWEENDAYS"(start_dt date, end_dt date)
  RETURN INT IS
  t_days INT;
BEGIN
  SELECT (TRUNC(end_dt - start_dt) - ((CASE
           WHEN (8 - to_number(to_char(start_dt, ‘D‘))) >
                TRUNC(end_dt - start_dt) + 1 THEN
            0
           ELSE
            trunc((TRUNC(end_dt - start_dt) -
                  (8 - to_number(to_char(start_dt, ‘D‘)))) / 7) + 1
         END) + (CASE
           WHEN MOD(8 - to_char(start_dt, ‘D‘), 7) >
                TRUNC(end_dt - start_dt) - 1 THEN
            0
           ELSE
            TRUNC((TRUNC(end_dt - start_dt) -
                  (MOD(8 - to_char(start_dt, ‘D‘), 7) + 1)) / 7) + 1
         END)))
    INTO t_days
    FROM dual;
  RETURN t_days;
END FUN_BETWEENDAYS;