如何使用excel表中的新数据更新sql server表?

I have managed to get data from an excel sheet into my SQL SERVER table through VB.net but every time I run the query (click the button), the same data is uploaded again to my table. Is there a way to import only the additional data ? (column 'Email' should be unique in my SQLSERVER table) Below is my code:I have managed to get data from an excel sheet