试着用这个
声明@date1 datetime，@date2 datetime；
选择@date1='8/1/2018'，@date2='8/7/2018'
选择datediff（dd，@date1，@date2）-（datediff（wk，@date1，@date2）*2）-case when datepart（dw，@date1）=1，然后选择1 else 0 end+case when datepart（dw，@date2）=1，然后选择1 else 0 end

DROP FUNCTION IF EXISTS GetNumberOfDays;

CREATE FUNCTION GetNumberOfDays(P_Date1 varchar(20), P_Date2 varchar(20))
   RETURNS int(100)
BEGIN
   DECLARE x         INT;
   DECLARE V_Date1   date;
   DECLARE V_Date2   date;
   SET V_Date1 := STR_TO_DATE(P_Date1, '%d/%m/%Y');
   SET V_Date2 := STR_TO_DATE(P_Date2, '%d/%m/%Y');
   SET x := 0;

   WHILE V_Date1 <= V_Date2
   DO
      IF (DAYOFWEEK(V_Date1) != 7 AND DAYOFWEEK(V_Date1) != 1)
      THEN
      BEGIN
          SET x = x + 1;
      END;
      END IF;

      SET V_Date1 := DATE_ADD(V_Date1, INTERVAL 1 DAY);
   END WHILE;

  RETURN x;
END;

SELECT GetNumberOfDays('01/08/2018', '11/08/2018')