CREATE OR REPLACE FUNCTION DAY_CALCULATOR
  ( latest_date IN DATE DEFAULT trunc(sysdate), 
    earliest_date IN DATE)
  RETURN  number IS
   nCounter                 Number := 0;
   tempDate                 Date;
BEGIN
    tempDate := trunc(earliest_date);
    loop
    nCounter := nCounter + 1;
    tempDate := tempDate + 1;
    exit when  tempDate > trunc(latest_date);
    end loop;
    RETURN nCounter;
EXCEPTION
   WHEN others THEN
       return 0;
END;

select dates,to_char(dates,'day') from (
select to_date('01-Aug-2007')+level-1 as dates 
from dual connect by level <= DAY_CALCULATOR(sysdate,'01-Aug-2007'))
where trim(to_char(dates,'day')) in('saturday','sunday');

floor(date1-date2)