如何在PostgreSQL中获取前一个工作日？

SELECT CASE 
         WHEN EXTRACT(ISODOW FROM current_date - interval '1 day') IN (6, 7) 
         THEN current_date - interval '1 day' - interval '1 day'
         ELSE current_date - interval '1 day'
       END AS previous_workday;

CREATE OR REPLACE FUNCTION get_previous_workday(date_val date)
  RETURNS date AS
$$
DECLARE
  previous_date date := date_val - interval '1 day';
BEGIN
  WHILE EXTRACT(ISODOW FROM previous_date) IN (6, 7) LOOP
    previous_date := previous_date - interval '1 day';
  END LOOP;
  
  RETURN previous_date;
END;
$$
LANGUAGE plpgsql;

SELECT get_previous_workday(current_date) AS previous_workday;