SQL Server: SqlBulkCopy import causes primary key violations

I am trying to design a window based application in C#.NET. I am reading csv file in data grid view and then insert those data into database. I am using SqlBulkCopy to insert data from csv file into database. My concern is, when I am trying to insert data into database (which already consist data) I am getting error of primary key constraint. I want to know whether it is possible to compare value before inserting into database using SqlBulkCopy. If value exist in database it should do update.

Can anyone provide me logic for this.

Thanks.