static DataTable SqlGetTabelle(string connectionString)
        {
            string query = "SELECT TABLE_NAME, TABLE_TYPE FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_TYPE = 'BASE TABLE' AND OBJECTPROPERTY(OBJECT_ID(TABLE_SCHEMA + '.' + TABLE_NAME), N'IsUserTable') = 1 AND OBJECTPROPERTY(OBJECT_ID(TABLE_SCHEMA + '.' + TABLE_NAME), N'IsMSShipped') = 0";
            SqlConnection connection = new SqlConnection(connectionString);
            SqlCommand command = new SqlCommand(query, connection);
            SqlDataAdapter adapter = new SqlDataAdapter(command);
            connection.Open();

            DataTable tabelle = new DataTable("TABLES");
            adapter.Fill(tabelle);

            connection.Close();

            return tabelle;
        }