We are seeing the exception org.springframework.dao.DataIntegrityViolationException: Hibernate operation: ORA-00001: unique constraint , when we are updating a coulmn(this column is not part of the constarint) with a value which had the null in database.
When we see the hibernate logs , insert query got generated here.


But , the update went fine , if the the column metioned above didnt have the null value. But here , update query got generated.

So , the question is , why is that "null" is a special case , for updation( eventhough it is not part of the constraint)