[vb.net] how to refresh my datagridview after I add new data

wish this will help Create Function

        private sub loaddata()
        datagridview.Datasource=nothing
        datagridview.refresh
        dim str as string = "select * from database"
      using cmd As New OleDb.OleDbCommand(str,cnn)
        using da As new OleDbDataAdapter(cmd)
          using newtable as new datatable
            da.fill (newtable)
            datagridview.datasource=newtable
          end using
       end using
     end using
end sub