difference between varchar nvarchar
If your column will store a fixed-length Unicode characters like French, Arabic and so on characters then go for NCHAR. If the data stored in a column is Unicode and can vary in length, then go for NVARCHAR. Querying to NCHAR or NVARCHAR is a bit slower then CHAR or VARCHAR. So don't go for NCHAR or NVARCHAR to store non-Unicode characters even though this data type supports that.