Working days b/w two days & Weekends b/w two dates

MySQL is very rich with built in function as it have thousands of functions. But apart from this rich library sometimes we need to create some custom function to get the task done. Today I encountered same kind of situation. I need a function which can return no. of working days between two dates and it should also return the weekend days between two days. Here is the solution for this problem. I created a user defined function to calculate working dates between two dates. 

In one week, there are 7 days but working days are Monday to Friday. 

• This function can calculate Days difference between two days. 
• Working days between two days (Excluding Saturday & Sunday). 
• Weekend days between two days (Saturday & Sunday).

  DELIMITER $$
  DROP FUNCTION IF EXISTS `DBName`.`getWorkingday`$$
  CREATE  FUNCTION `getWorkingday`(d1 datetime,d2 datetime, retType varchar(20)) RETURNS varchar(255) CHARSET utf8
  BEGIN
 DECLARE dow1, dow2,daydiff,workdays, weekenddays, retdays,hourdiff INT;
    declare newstrt_dt datetime;
   SELECT dd.iDiff, dd.iDiff - dd.iWeekEndDays AS iWorkDays, dd.iWeekEndDays into daydiff, workdays, weekenddays
  FROM (
   SELECT
     dd.iDiff,
     ((dd.iWeeks * 2) + 
      IF(dd.iSatDiff >= 0 AND dd.iSatDiff < dd.iDays, 1, 0) + 
      IF (dd.iSunDiff >= 0 AND dd.iSunDiff < dd.iDays, 1, 0)) AS iWeekEndDays
       FROM (
      SELECT  dd.iDiff, FLOOR(dd.iDiff / 7) AS iWeeks, dd.iDiff % 7 iDays, 5 - dd.iStartDay AS iSatDiff,  6 - dd.iStartDay AS iSunDiff
     FROM (
      SELECT
        1 + DATEDIFF(d2, d1) AS iDiff,
        WEEKDAY(d1) AS iStartDay
      ) AS dd
    ) AS dd
  ) AS dd ;
  if(retType = 'day_diffs') then
  set retdays = daydiff; 
 elseif(retType = 'work_days') then
  set retdays = workdays; 
 elseif(retType = 'weekend_days') then  
  set retdays = weekenddays; 
 end if; 
    RETURN retdays; 
    END$$
  DELIMITER ;

Normal Days difference

    select getWorkingday('2012-09-01 15:43:59','2012-09-20 15:43:59','day_diffs') as result;
    result: 20

Working days between two dates (Excluding Saturdays & Sundays)

    select getWorkingday('2012-09-01 15:43:59','2012-09-20 15:43:59','work_days') as result;
    result: 14

Weekends between two days (Saturdays & Sundays)

   select getWorkingday('2012-09-01 15:43:59','2012-09-10 15:43:59','weekend_days') as result;
   result: 6