ช่วยชี้แนะหน่อยครับ เรื่องการใช้คำสั่งอัพเดทข้อมูลทุกเรคคอร์ดในครั้งเดียว

Private Sub Button5_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button5.Click
        Dim objConn As New System.Data.SqlClient.SqlConnection
        Dim dtAdapter As System.Data.SqlClient.SqlDataAdapter
        Dim dt As New DataTable
        Dim ds As New DataSet
        Dim objCmd As New SqlCommand
        Dim intNumRows As Double


        Dim strConnString, strqr, aaaaa As String
        strConnString = "Server=IT-04S\SQLEXPRESS;UID=TestVB;PASSWORD=11111;database=TestVB;Max Pool Size=400;Connect Timeout=600;"
        objConn = New System.Data.SqlClient.SqlConnection(strConnString)
        objConn.Open()

        Dim strSQL As String
        strSQL = "SELECT IdEmp,NameEmp FROM ReportSl "
        aaaaa = objCmd.ExecuteScalar

        dtAdapter = New System.Data.SqlClient.SqlDataAdapter(strSQL, objConn)
        dtAdapter.Fill(dt)

        dtAdapter = Nothing
        objConn.Close()
        objConn = Nothing


        For i = 0 To dt.Rows.Count - 1

            strSQL = "SELECT sum(SUM_CN) FROM QDAILY WHERE CODE = '" & aaaaa & "'"
            objCmd = New SqlCommand(strSQL, objConn)
            Try
                intNumRows = objCmd.ExecuteScalar()
                Label4.Text = intNumRows.ToString()
                Me.Label8.Text = intNumRows
            Catch ex As Exception
                Me.Label8.Text = intNumRows
            End Try

            ' '''''''''''''''''''''''''รวมค่าเสร็จแล้ว บัณทึกลงฐานข้อมูล''''''''''''''''''''''''''''''

            strqr = "UPDATE ReportSL SET CNsum = " & Me.Label8.Text & " WHERE IdEmp = '" & aaaaa & "'"

            objCmd = New SqlCommand(strqr, objConn)

            Try
                objCmd.ExecuteNonQuery()
                Me.Label3.Text = "อัพเดทข้อมูลสำเร็จ"
            Catch ex As Exception
                Me.Label3.Text = "ไม่สามารถบันทึกข้อมูล"
            End Try



        Next

    End Sub