SQL để trả về số ngày làm việc giữa 2 ngày đã qua

Thật đơn giản:

    SQL> Select count(*)
      2  from ( select rownum rnum
      3          from all_objects
      4        where rownum <= to_date('18-dec-2009','dd-mon-yyyy') - 
    to_date('16-nov-2009')+1 )
      5    where to_char( to_date('16-nov-2009','dd-mon-yyyy')+rnum-1, 'DY' )
      6                not in ( 'SAT', 'SUN' )


      COUNT(*)
    ----------
            25

    SQL> Select to_char( to_date('16-nov-2009','dd-mon-yyyy')+rnum-1, 'DY dd-mon-yyyy' )
      2  from ( select rownum rnum
      3          from all_objects
      4        where rownum <= to_date('18-dec-2009','dd-mon-yyyy') - to_date('16-nov-2009')+1 )
      5    where to_char( to_date('16-nov-2009','dd-mon-yyyy')+rnum-1, 'DY' )
      6                not in ( 'SAT', 'SUN' )


DAY_DATE
---------------
MON 16-nov-2009
TUE 17-nov-2009
WED 18-nov-2009
THU 19-nov-2009
FRI 20-nov-2009
MON 23-nov-2009
TUE 24-nov-2009
WED 25-nov-2009
THU 26-nov-2009
FRI 27-nov-2009
MON 30-nov-2009
TUE 01-dec-2009
WED 02-dec-2009
THU 03-dec-2009
FRI 04-dec-2009
MON 07-dec-2009
TUE 08-dec-2009
WED 09-dec-2009
THU 10-dec-2009
FRI 11-dec-2009
MON 14-dec-2009
TUE 15-dec-2009
WED 16-dec-2009
THU 17-dec-2009
FRI 18-dec-2009

25 rows selected.