System generated excel import to SQL

Dim excelPath As String = Server.MapPath("~/Uploads/") + Path.GetFileName(FileUpload1.PostedFile.FileName)
FileUpload1.SaveAs(excelPath)

Dim connString As String = String.Empty
Dim extension As String = Path.GetExtension(FileUpload1.PostedFile.FileName)
Select Case extension
    Case ".xls"
        'Excel 97-03
        connString = ConfigurationManager.ConnectionStrings("Excel03ConString").ConnectionString
        Exit Select
    Case ".xlsx"
        'Excel 07 or higher
        connString = ConfigurationManager.ConnectionStrings("Excel07+ConString").ConnectionString
        Exit Select
End Select

connString = String.Format(connString, excelPath)
Using excel_con As New OleDbConnection(connString)
    excel_con.Open()
    Dim sheet1 As String = excel_con.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, Nothing).Rows(0)("TABLE_NAME").ToString()
    Dim dtExcelData As New DataTable()

    Using oda As New OleDbDataAdapter((Convert.ToString("SELECT * FROM [") & sheet1) + "]", excel_con)
        oda.Fill(dtExcelData)
    End Using
    excel_con.Close()

    Dim conString As String = ConfigurationManager.ConnectionStrings("SQLDbConnection").ConnectionString
    Using con  As New SqlConnection(conString)
        Using sqlBulkCopy As New SqlBulkCopy(con)
            'Set the database table name
            sqlBulkCopy.DestinationTableName = "dbo.TESTTBL"
            con.Open()
            sqlBulkCopy.WriteToServer(dtExcelData)
            con.Close()
        End Using
    End Using
End Using