Need help! Can't validate date overlaps for a tabular column

Question

Hello all,
The validation I created to validate whether new or updates rows does not overlap with any records in the table isn't working.
The columns are StartDt and EndDt
Validation Type: NOT EXISTS
Validation expresion:
select 1
    from  sample S
    WHERE S.STARTDT BETWEEN :STARTDT AND :ENDDT
OR(S.ENDDT BETWEEN :STARTDT AND :ENDDT)
or (S.STARTDT <= :STARTDT and S.ENDDT >= :ENDDT)
or (:STARTDT <= S.STARTDT and :ENDDT >= S.ENDDT)
Error Message:
Times overlap
When Buttons pressed
-Select Button-
The validation works if a new row or updated row overlaps any existing start and end date records but it doesn't work if I update startdate and end date rows that doesn't overlap existing date times
Example:
TABLE DISPLAYS THE FOLLOWING RECORDS
NAME                   START DATE                      END DATE
TEST                    1/1/2012                               12/31/2012
If I update the rows to the following values, I receive an error message (although those values don't overlap any records in the table)
NAME                   START DATE                      END DATE
TEST                    6/1/2012                               10/30/2012
Any ideas? Do I need to change my code?
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Message was edited by: CharlieMack

Answer 1

Logic for date range overlap testing only requires two conditions in the WHERE clause:
ORACLE-BASE - Overlapping Date Ranges
WHERE S.STARTDT <= :ENDDT AND S.ENDDT >= :STARTDT -- TRUE for ranges that overlap
It looks a little odd, but, if you scribble out a 'logic table', it makes sense.
Condition
A.start <= B.end
A.end >= B.start
A__A B--B
true
false
A__B=A--B
true
true
A__B==B__A
true
true
B--A==B__A
true
true
B--B A__A
false
true
MK