Interestingly enough, even though one "null" does not equal another "null", i.e. any comparison with NULL is always false, a unique index on (col1, col2) throws a unqiue constraint violation when you insert a second (1,null). It appears that for the index (1,null) IS equal to (1,null) - or does the unique index use reverse logic and checks if (1,null) <> (1,null) and, since this is false, concludes that (1,null) must be equal (1,null) and therefore violate the constraint ;-)
Jared Still wrote:
> A unique constraint can be used for this. > > Have you tried it? > > -- > Jared Still > Certifiable Oracle DBA and Part Time Perl Evangelist
-- Regards
Wolfgang Breitling Centrex Consulting Corporation www.centrexcc.com -- http://www.freelists.org/webpage/oracle-l
