计算两个日期之间的工作日Oracle

CREATE TABLE workdays (
  workday DATE PRIMARY KEY
);

-- 假设工作日从周一到周五
INSERT INTO workdays (workday)
SELECT TRUNC(SYSDATE) - LEVEL + 1
FROM DUAL
CONNECT BY LEVEL <= TRUNC(SYSDATE) - TRUNC(SYSDATE, 'YYYY') + 1
WHERE TO_CHAR(TRUNC(SYSDATE) - LEVEL + 1, 'D') BETWEEN 2 AND 6;

CREATE OR REPLACE FUNCTION get_workdays(start_date IN DATE, end_date IN DATE)
  RETURN NUMBER
IS
  workday_count NUMBER := 0;
BEGIN
  SELECT COUNT(*)
  INTO workday_count
  FROM workdays
  WHERE workday >= start_date AND workday <= end_date;

  RETURN workday_count;
END;

SELECT get_workdays(DATE '2022-01-01', DATE '2022-01-31') AS workday_count
FROM DUAL;