/// <summary>
        /// Adds a flight item
        /// </summary>
        /// <param name="source">New item to be added.</param>
        /// <returns>The id of the newly created item.</returns>
        public async Task <Bm> AddAsync(Bm source)
        {
            #region SQL-query: INSERT INTO flights
            const string sqlQuery =
                "INSERT INTO " +
                "flights (name, \"from\", \"to\", airline_id, flight_type_id, tourist_info_edit_lock, return_flight_same_airline_required, alternative_search, flight_duration, airplane_model_id, status_id) " +
                "VALUES (@Name, @From, @To, @AirlineId, @FlightTypeId, @TouristInfoEditLock, @ReturnFlightSameAirlineRequired, @AlternativeSearch, @FlightDuration, @AirplaneModelId, @StatusId) " +
                "RETURNING id AS Id";
            #endregion

            var entity = _mapper.Map <Entity>(source);

            using var conn = _conn.GetConnection();
            entity.Id      = await conn.QuerySingleAsync <long>(sqlQuery, entity);

            return(_mapper.Map <Bm>(entity));
        }
        /// <summary>
        /// Partial update of a record
        /// </summary>
        /// <param name="id">Id of a record.</param>
        /// <param name="property">Column name in database.</param>
        /// <param name="model">New value.</param>
        /// <returns>Updated item.</returns>
        public async Task <Bm> PatchRecordAsync(long id, string property, Bm model)
        {
            var tablePropertyName = AllowedColumns.GetValueOrDefault(property);

            #region SQL-query: UPDATE flights SET
            string sqlQueryUpdate = $"UPDATE flights SET {tablePropertyName}=@{property} WHERE id=@id;";
            #endregion
            #region SQL-query: SELECT FROM flights
            const string sqlQuerySelect =
                "WITH aggtab AS( " +
                "SELECT * " +
                "FROM flight_dates fd " +
                "INNER JOIN flights fl ON fd.flight_id = @soughtId " +
                "WHERE current_timestamp<fd.departure_date " +
                "ORDER BY fd.departure_date-current_timestamp ASC " +
                "), " +
                "nearest_dates AS( " +
                "SELECT fd.flight_id, fd.departure_date, fd.arrival_date " +
                "FROM flight_dates fd " +
                "INNER JOIN (SELECT aggtab.flight_id, MIN(aggtab.departure_date) AS NearestDepDate " +
                "FROM aggtab " +
                "GROUP BY aggtab.flight_id) nd ON nd.flight_id = fd.flight_id " +
                "WHERE fd.departure_date = nd.NearestDepDate " +
                ") " +
                "SELECT " +
                "fl.id AS Id, " +
                "fl.name AS Name, " +
                "fl.from AS \"From\", " +
                "fl.to AS \"To\", " +
                "nd.departure_date AS NearestDepartureDate, " +
                "nd.arrival_date AS NearestArrivalDate, " +
                "fl.airline_id AS AirLineId, " +
                "fl.flight_type_id AS FlightTypeId, " +
                "fl.tourist_info_edit_lock AS TouristInfoEditLock, " +
                "fl.return_flight_same_airline_required AS ReturnFlightSameAirlineRequired, " +
                "fl.alternative_search AS AlternativeSearch, " +
                "fl.flight_duration AS FlightDuration, " +
                "fl.airplane_model_id AS AirplaneModelId, " +
                "fl.status_id AS StatusId, " +
                "false AS IsReturnFlight, " +
                "fl.id, " +
                "rf.flight_from_id AS ReturnId " +
                "FROM flights fl " +
                "LEFT JOIN return_flights rf ON fl.id = rf.flight_to_id " +
                "LEFT JOIN nearest_dates nd ON nd.flight_id = fl.id " +
                "WHERE fl.id=@soughtId;";
            #endregion

            var dateDictionary = new Dictionary <long?, Bm>();

            var entity = _mapper.Map <Entity>(model, opt => { opt.AfterMap((model, dest) => dest.Id = id); });

            using var conn = _conn.GetConnection();
            await conn.ExecuteAsync(sqlQueryUpdate, entity);

            return((await conn.QueryAsync <Bm, ReturnFlightIdsHelper, Bm>(sqlQuerySelect, (flight, retFlightId) =>
            {
                if (!dateDictionary.TryGetValue(flight.Id, out Bm flightEntry))
                {
                    flightEntry = flight;
                    flightEntry.ReturnFlightIds = new List <long>();
                    dateDictionary.Add(flightEntry.Id, flightEntry);
                }
                flightEntry.ReturnFlightIds.Add(retFlightId.ReturnId);

                return flightEntry;
            }, new { soughtId = id })).Distinct().SingleOrDefault());
        }