Question

我问的是WHERE子句。我搜索了互联网，但我没有找到我的问题的答案。

我有几个实体类，我在下面代表：

tranformed_rows

我的问题是为什么这个查询不能正常工作。返回的列表是空的，但是数据库中存在记录，当我想要返回所有Trasa记录时，一切正常，只有在我添加带有raport属性的WHERE子句时才起作用。

 @NamedQuery(name = "selectTrasy",
    query = "SELECT t FROM Trasa t WHERE t.raport = :raport ORDER BY t.id")
@Entity
public class Trasa  implements Serializable {
@Id
@Column(name = "id", unique = true )
@GeneratedValue
private Long id;

@Column(name = "data_z")
private Date dataz;

@Column(name = "data_do")
private Date datado;

@Column(name = "czas_z")
private String czasZ;

@Column(name = "czas_do")
private String czasDo;

@OneToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "miejscowosc_z")
private MiejscowoscDB miejscowoscZ;

@OneToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "miejscowosc_do")
private MiejscowoscDB miejscowoscDo;

@OneToOne(fetch = FetchType.LAZY)
private Uzytkownik user;

@OneToOne(fetch = FetchType.LAZY)
private Raport raport;

@Override
public boolean equals(Object other) {
    return (other != null && getClass() == other.getClass() && id != null)
        ? id.equals(((Trasa) other).id)
        : (other == this);
}

@Override
public int hashCode() {
    return (id != null) 
        ? (getClass().hashCode() + id.hashCode())
        : super.hashCode();
}

//next I have getters and setters
}


 @Entity
 public class Raport  implements Serializable {
@Id
@Column(name = "id", unique = true )
@GeneratedValue
private Long id;

@Column(name = "data")
private Date data;

@Column(name = "nazwa")
private String nazwa;

@Enumerated(EnumType.STRING)
private Powod powod;

@OneToOne(fetch = FetchType.LAZY)
private Uzytkownik uzytkownik;


@Override
public boolean equals(Object other) {
    return (other != null && getClass() == other.getClass() && id != null)
        ? id.equals(((Raport) other).id)
        : (other == this);
}

@Override
public int hashCode() {
    return (id != null) 
        ? (getClass().hashCode() + id.hashCode())
        : super.hashCode();
}
 //getters and setters
 }

Answer 1

将您的查询更改为：

 @NamedQuery(name = "selectTrasy",
    query = "SELECT t FROM Trasa t WHERE t.raport.id = :raportId ORDER BY t.id")

然后像这样运行：

trasy = (List<Trasa>)(manager.createNamedQuery("selectTrasy")
            .setParameter("raportId", propertyWydatek.getRaport().getId())
            .getResultList());

其他版本的查询：

 @NamedQuery(name = "selectTrasy",
    query = "SELECT t FROM Trasa t join t.raport r WHERE r.id = :raportId ORDER BY t.id")

JPA WHERE子句

1 个答案: