Prevent inserting overlapping date ranges using a SQL trigger

select *
  from testdatetrigger t
   join inserted i
   on ((i.ValidTo >= t.ValidFrom) and (i.ValidFrom <= t.ValidTo))
  Where not (i.ValidTo=t.Validto and i.ValidFrom=t.ValidFrom)

This can be applied to the numbers as well.

Please refer the link

http://stackoverflow.com/questions/4023160/prevent-inserting-overlapping-date-ranges-using-a-sql-trigger