How To Check There Is No Item In Table?

Hi,
I want to check that Is there row exists in table or not.
Please correct me. 
 
        Dim conn As SqlConnection
        Dim comm As SqlCommand
        Dim reader As SqlDataReader

        Dim connstring As String

        connstring = ConfigurationManager.ConnectionStrings("iharyana").ConnectionString

        conn = New SqlConnection(connstring)

        comm = New SqlCommand("select * from test where username=@username", conn)

        comm.Parameters.Add("@username", Data.SqlDbType.VarChar, 20)
        comm.Parameters("@username").Value = uname

        conn.Open()
        reader = comm.ExecuteReader

        While reader.Read

            If reader.Item("username").ToString = "" Then
                Response.Redirect("http://www.iharyana.com")
            End If

       
        End While

        reader.Close()
        conn.Close()