Question

现在我的查询返回航班地图及其机票计数。我的目标是从查询结果(count(t) < f.aircraft.model.passengersSeatsQuantity)中排除完整的航班。但我无法设法创建这样的查询。因此，现在我必须在方法中排除完整的航班，这令人沮丧，因为我认为应该有办法在查询中进行。任何人都可以帮助构建查询？附：我现在可以使用Criteria API

String queryString = "SELECT f, COUNT(t)"
            + " FROM Flight f"
            + " JOIN FETCH f.tickets AS t"
            + " WHERE f.departureAirport=:departureAirport"
            + " GROUP BY t.flight"
            + " ORDER BY f.id ASC";

Query query = em.createQuery(queryString);
query.setParameter("departureAirport", departureAirport);

Map<Flight, Long>) flightsTicketCountMap =
            query.getResultList().stream()
            .collect(Collectors.toMap(resultElement -> (Flight) (((Object[]) resultElement)[0]),
                    resultElement -> (Long) (((Object[]) resultElement)[1])));

//below i exclude full flights from map, but i want to do it in query
Map<Flight, Long> availableFlightTicketPriceMap = new HashMap();
for (Map.Entry<Flight, Long> entry : flightsTicketCountMap.entrySet()) {
        flight = entry.getKey();
        ticketsQuantity = entry.getValue();
        if (flight.getAircraft().getModel().getPassengersSeatsQuantity() > ticketsQuantity) {
            availableFlightTicketPriceMap.put(flight, calculateTicketPrice(tariffsDetails, flight, ticketsQuantity));
        }
    }

更新。飞机和型号都有急切的政策，但HAVING COUNT(t) < f.aircraft.model.passengersSeatsQuantity热点异常com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Unknown column aircraftmo3_.passenger_seats_quantity in having clause

public class Flight{
@OneToOne(fetch = FetchType.EAGER) 
@JoinColumn(name = "aircraft_id")
    private Aircraft aircraft;
}

public class Aircraft{
  @ManyToOne(fetch = FetchType.EAGER)
  @JoinColumn(name = "model_id")
  private AircraftModel model;
}

public class AircraftModel{
  @Column(name = "passenger_seats_quantity")
  @Range(min = 0, max = 450)
  private Integer passengersSeatsQuantity;
}

Answer 1

您是否尝试过添加HAVING条款？

SELECT f, COUNT(t)
FROM Flight f
JOIN FETCH f.tickets AS t
WHERE f.departureAirport=:departureAirport
GROUP BY t.flight
HAVING COUNT(t) < f.aircraft.model.passengersSeatsQuantity
ORDER BY f.id ASC

如何将HQL子句（WHERE COUNT（）＆lt; MAX_VAL）添加到复杂查询中

1 个答案: