Difference between 2 timestamp,not considering the weekends (SATURDAY,SUN)

Question

I use an Oracle XE and I have a table which has the following Timestamp columns
A_Date Timestamp
R_Date Timestamp
Now in this query i need to be able to exclude the SAT/SUN and show the difference between these 2 timestamp dates.
Could any one help on this?
I use this query to find out the difference between the 2 dates (R_DATE - A_DATE),showing the DAYS:HOURS:MIN:SECS
TRUNC (TO_NUMBER (SUBSTR ((R_DATE - A_DATE),
1,
INSTR (R_DATE - A_DATE, ' ')
|| ':'
|| SUBSTR ((R_DATE - A_DATE),
INSTR ((R_DATE - A_DATE), ' ') + 1,
2
|| ':'
|| SUBSTR ((R_DATE - A_DATE),
INSTR ((R_DATE - A_DATE), ' ') + 4,
2
|| ':'
|| SUBSTR ((R_DATE - A_DATE),
INSTR ((R_DATE - A_DATE), ' ') + 7,
2
) "TTR"
Example : A_DATE := '11-Dec-2009 19:33:30 PM' ---> Friday
R_DATE := '14-Dec-2009 07:32:38 AM' ---> Monday
should not consider the SAT/SUN that comes between them.
Thanks
GAG

Answer 1

SQL> create table t as (
  2  select to_timestamp('11-dec-2009 07:33:30 PM') rdate
  3  ,      to_timestamp('14-dec-2009 07:32:38 AM') adate
  4  from   dual
  5  );
Table created.
SQL> select rdate
  2  ,      adate
  3         /* do some final formatting */
  4  ,      to_number(substr(diff_incl_weekend, 1, instr( diff_incl_weekend, chr(32))))
  5         ||':'||
  6         substr(diff_incl_weekend, instr( diff_incl_weekend, chr(32))+1, 8) diff_incl_weekend
  7  ,      to_number(substr(diff_excl_weekend, 1, instr( diff_excl_weekend, chr(32))))
  8         ||':'||
  9         substr(diff_incl_weekend, instr( diff_excl_weekend, chr(32))+1, 8) diff_excl_weekend    
10  from ( /* substract intervals */
11         select to_char(rdate, 'dd-mon-yyyy hh:mi:ss AM') rdate
12         ,      to_char(adate, 'dd-mon-yyyy hh:mi:ss AM') adate
13         ,      trim('+'
14                from
15                numtodsinterval((to_date(to_char(adate, 'dd-mon-yyyy hh:mi:ss AM'), 'dd-mon-yyyy hh:mi:ss AM')
16                                 -
17                                 to_date(to_char(rdate, 'dd-mon-yyyy hh:mi:ss AM'), 'dd-mon-yyyy hh:mi:ss AM')
18                                )
19                               , 'day')
20                    ) diff_incl_weekend
21         ,      trim('+'
22                from            
23                numtodsinterval((to_date(to_char(adate, 'dd-mon-yyyy hh:mi:ss AM'), 'dd-mon-yyyy hh:mi:ss AM')
24                                 -
25                                 to_date(to_char(rdate, 'dd-mon-yyyy hh:mi:ss AM'), 'dd-mon-yyyy hh:mi:ss AM')
26                                 -
27                                 nof_satsuns.total
28                                )
29                               , 'day')
30                    ) diff_excl_weekend
31         from   t
32         ,      /* calculate nof sats and suns*/
33              ( select count(dy) total
34                from ( select to_char(rdate+level-1, 'dy') dy
35                       from   t
36                       where  to_char(rdate+level-1, 'dy', 'nls_date_language=american') in ('sat','sun')
37                       connect by level <= trunc(to_date(to_char(adate, 'dd-mon-yyyy hh:mi:ss AM'), 'dd-mon-yyyy hh:mi:ss AM'))
38                                           -
39                                           trunc(to_date(to_char(rdate, 'dd-mon-yyyy hh:mi:ss AM'), 'dd-mon-yyyy hh:mi:ss AM'))+1
40                     )    
41              ) nof_satsuns
42      );
RDATE                   ADATE                   DIFF_INCL_WEEKEND                                 DIFF_EXCL_WEEKEND
11-dec-2009 07:33:30 PM 14-dec-2009 07:32:38 AM 2:11:59:08                                        0:11:59:08