Npgsql.NpgsqlConnection.Open C# (CSharp) Method

        public override void Open()
        {
            // If we're postponing a close (see doc on this variable), the connection is already
            // open and can be silently reused
            if (_postponingClose)
                return;

            CheckConnectionClosed();

            NpgsqlEventLog.LogMethodEnter(LogLevel.Debug, CLASSNAME, "Open");

            // Check if there is any missing argument.
            if (!settings.ContainsKey(Keywords.Host))
            {
                throw new ArgumentException(resman.GetString("Exception_MissingConnStrArg"),
                                            NpgsqlConnectionStringBuilder.GetKeyName(Keywords.Host));
            }
            if (!settings.ContainsKey(Keywords.UserName) && !settings.ContainsKey(Keywords.IntegratedSecurity))
            {
                throw new ArgumentException(resman.GetString("Exception_MissingConnStrArg"),
                                            NpgsqlConnectionStringBuilder.GetKeyName(Keywords.UserName));
            }

            // Get a Connector, either from the pool or creating one ourselves.
            if (Pooling)
            {
                connector = NpgsqlConnectorPool.ConnectorPoolMgr.RequestConnector(this);
            }
            else
            {
                connector = new NpgsqlConnector(this);

                connector.ProvideClientCertificatesCallback += ProvideClientCertificatesCallbackDelegate;
                connector.CertificateSelectionCallback += CertificateSelectionCallbackDelegate;
                connector.CertificateValidationCallback += CertificateValidationCallbackDelegate;
                connector.PrivateKeySelectionCallback += PrivateKeySelectionCallbackDelegate;
                connector.ValidateRemoteCertificateCallback += ValidateRemoteCertificateCallbackDelegate;

                connector.Open();
            }

            connector.Notice += NoticeDelegate;
            connector.Notification += NotificationDelegate;

            if (SyncNotification)
            {
                connector.AddNotificationThread();
            }

            if (Enlist)
            {
                Promotable.Enlist(Transaction.Current);
            }

            this.OnStateChange (new StateChangeEventArgs(ConnectionState.Closed, ConnectionState.Open));

        }

 /// <summary>
 /// Get all CBS neighbourhoods, specifically its name, boundary (in WKT), and center.
 /// </summary>
 public void Enhance(IEnumerable<LocationDescription> locationDescriptions)
 {
     using (var conn = new NpgsqlConnection(connectionString))
     {
         conn.Open();
         var streets = new List<string>();
         foreach (var locationDescription in locationDescriptions)
         {
             var query = string.Format(Query, locationDescription.RdBoundary);
             using (var command = new NpgsqlCommand(query, conn))
             {
                 try
                 {
                     using (var dr = command.ExecuteReader())
                     {
                         while (dr.Read())
                         {
                             streets.Add(dr["straat"].ToString());
                         }
                     }
                 }
                 catch (SystemException e)
                 {
                     Console.WriteLine(e.Message);
                 }
             }
             locationDescription.Features.Add("straten", string.Join(";", streets));
         }
     }
 }