Dear, friend:
You can set the DataKeyNames of the FormView to you PK in the DB.
<asp:FormView ID="FormView1" runat="server" OnItemUpdating="FormView1_ItemUpdating"
AllowPaging="True" DataKeyNames="ProductID" DataSourceID="SqlDataSource3" OnDataBinding="FormView1_DataBinding">
And retrive it in code behind as following:
this.FormView1.DataKey["name"].ToString();
I hope the above information will be helpful. If you have any issues or concerns, please let me know. It's my pleasure to be of assistance