I have inherited a database with data missing from Key columns
I want to create a unique index to prevent duplicates, the problem is above
I want 5 non null columns
Cname, Sname, Add_1, DOB, CountyID
There is null values in the DOB column, is there a way of creating an index on these columns from this point on? or do I need to populate the DOB (Date) column before I can create and index.