ทำ Form ค้นหาข้อมูลหลายตารางแต่ต้องการแสดงใน GridView อันเดียวครับ asp.net by vb.net

    Dim objConn As SqlConnection
    Dim objCmd As SqlCommand

    Sub Page_Load(sender As Object, e As EventArgs)
		Dim strConnString As String
		strConnString = "Server=localhost;Uid=sa;PASSWORD=;database=mydatabase;Max Pool Size=400;Connect Timeout=600;"
		objConn = New SqlConnection(strConnString)
		objConn.Open()

        BindData()
    End Sub

   Sub BindData()
	   Dim strSQL As String
	   strSQL = ""
	   strSQL = strSQL & "SELECT Col1,Col2,Col3 FROM customer1 WHERE Col1 LIKE '%" & strKeyword & "%' "
	   strSQL = strSQL & "UNION ALL "
	   strSQL = strSQL & "SELECT Col1,Col2,Col3 FROM customer2 WHERE Col1 LIKE '%" & strKeyword & "%'"
	   strSQL = strSQL & "UNION ALL "
	   strSQL = strSQL & "SELECT Col1,Col2,Col3 FROM customer3 WHERE Col1 LIKE '%" & strKeyword & "%'"

	   Dim dtReader As SqlDataReader
	   objCmd = New SqlCommand(strSQL, objConn)
	   dtReader = objCmd.ExecuteReader()

	   '*** BindData to GridView ***'
	   myGridView.DataSource = dtReader
	   myGridView.DataBind()

	   dtReader.Close()
	   dtReader = Nothing

   End Sub

   Sub Page_UnLoad()
	   objConn.Close()
	   objConn = Nothing
   End Sub