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我在这个实体之间有一个双向的一对多关系，所有这些都是由 Netbeans 的 JPA 向导创建的

车辆（车辆）

@Entity
@Table(name = "vehiculo")
@XmlRootElement
@NamedQueries({
@NamedQuery(name = "Vehiculo.findAll", query = "SELECT v FROM Vehiculo v"),
@NamedQuery(name = "Vehiculo.findById", query = "SELECT v FROM Vehiculo v WHERE v.id =    :id")})
public class Vehiculo implements Serializable {

  //more attributes

  @OneToMany(cascade = CascadeType.ALL, mappedBy = "idVehiculo", fetch =  FetchType.LAZY)
  private List<PuntoTrayecto> puntoTrayectoList;

  //methods
}

PuntoTrayecto (TrayectoryPoint)

@Entity
@Table(name = "punto_trayecto")
@XmlRootElement
public class PuntoTrayecto implements Serializable {

  //more attributes

  @JoinColumn(name = "id_vehiculo", referencedColumnName = "id")
  @ManyToOne(optional = false, fetch = FetchType.LAZY)
  private Vehiculo idVehiculo;

}

我需要通过 id 获取“Vehiculo”，因此我将 NamedQuery 称为“Vehiculo.findById”

    Query query = em.createNamedQuery("Vehiculo.findById");
    query.setParameter("id", 1);
    Object o = query.getSingleResult();
    Vehiculo vehiculo = (Vehiculo)o;

我得到这个例外：

Internal Exception: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException:  You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'precision, tiempo, velocidad, id_vehiculo FROM punto_trayecto WHERE (id_vehiculo' at line 1

这是试图调用的查询

Call: SELECT id, latitud, longitud, precision, tiempo, velocidad, id_vehiculo FROM punto_trayecto WHERE (id_vehiculo = ?)

它对应于另一个实体“PuntoTrayecto”，我猜这个 SELECT 查询被调用来填充“Vehiculo”的列表 puntoTrayectoList，如果我使用 JPA 控制器也会发生同样的情况。怎么了？

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1 回答 1

3

该问题可能是由列引起的precision。这是一个保留字（根据 MySQL）。您可以检查此答案以获取解决方法

于 2013-06-13T18:18:43.217 回答