I have a table that has around 5000 records. I have a requirement that i want to change a varchar column to UNIQUE, but the problem is that there are many rows that has empty values in it. If i try to change the column to UNIQUE, i am getting an error that "The CREATE UNIQUE INDEX statement terminated because a duplicate key was found for the object name. The duplicate key value is ()". My requirement is that the Column should have a Unique values in select cases while adding a new rows, sometimes null values can also be present. Is there a way for me to create a UNIQUE for that column. If i create a Trigger will that work out? If so how.