Actually, yes there is a concept here of overlapping. I used your query and it did not work for all cases. I went on Oracles website and found the answer there. Here is the link:

http://asktom.oracle.com/pls/ask/f?p=4950:8:15236886734525876868::NO::F4950_P8_DISPLAYID,F4950_P8_CRITERIA:4921012347969,

and we said... Do you need to be concerned with all overlaps? Eg: in database you have

01-jan-2001 07-jan-2001

you are given as inputs:

  15-dec-2000     15-jan-2001   - wider then database
  15-dec-2000     04-jan-2001   - overlaps but not contained within
  04-jan-2001     15-jan-2001   - overlaps but not contained within
  02-jan-2001     04-jan-2001   - overlaps and contained within
[download]

should all four return a "hit"?

select *
  from t
  where ( c_beginning between p_beginning and p_ending      -- rule 1
       OR c_ending between p_beginning and p_ending         -- rule 2
       OR ( c_beginning < p_beginning and p_ending < c_ending ) );  --
+ rule 3
[download]

will do that. If you use the following "chart", it depicts all of the possibles and which "rule" in the predicate above will catch them:

.............................................
             CB                CE
PB                                     PE     -- rule 1
PB                   PE                       -- rule 1
                     PB                PE     -- rule 2
                  PB     PE                   -- rule 3
PB  PE                                        -- no hit
                                        PB PE -- no hit
[download]

Thanks,
data