Question

我正在开发一个必须显示有关车辆详细信息的数据/信息的应用程序。我有2个表make和model，其中make_id是model表中的外键。我有2个实体类Make和Model，如下所示：

@Entity
@Table(name = "make")
@PrimaryKeyJoinColumn(name="make_id")
public class Make {
    @Id
    @Column(name = "make_id")
    private String makeId;

    @Column(name = "make_name")
    private String makeName;

    @ManyToOne
    @JoinColumn(name = "mfg_unit_id")
    private MfgUnit mfgUnit;

    // Getter and Setters
}


@Entity
@Table(name = "model")
public class Model {
    @Id
    @Column(name = "model_id")
    private String modelId;

    @Column(name = "model_creation_date")
    private Date modelCreationDate;

    @Column(name = "make_id")
    private long makeId;

    @ManyToOne
    @JoinColumn(name = "make_id")
    private Make make;

    // Getter and Setters
}

我能够检索所有Make，但是我的要求是仅检索Make在今天和过去30天之间的model_creation_date。有人可以帮助我如何建立休眠标准吗？

Answer 1

可能还有另一种解决方案，但是要实现此目的，您需要修改Make类，如下所示：与Model类引入新的关系（@OneToMany）：

@Entity
@Table(name = "make")
@PrimaryKeyJoinColumn(name="make_id")
public class Make {
    @Id
    @Column(name = "make_id")
    private String makeId;

    @Column(name = "make_name")
    private String makeName;

    // ** introduced new relationship **
    @OneToMany(mappedBy="make", fetch = FetchType.LAZY)
    private List<Model> models;

    @ManyToOne
    @JoinColumn(name = "mfg_unit_id")
    private MfgUnit mfgUnit;

    // Getter and Setters
}

并保持'Model'类不变：

@Entity
@Table(name = "model")
public class Model {
    @Id
    @Column(name = "model_id")
    private String modelId;

    // change the datatype as Date or similar Datatype
    @Column(name = "model_creation_date")
    private Date modelCreationDate;

    @Column(name = "make_id")
    private long makeId;

    @ManyToOne
    @JoinColumn(name = "make_id")
    private Make make;

    // Getter and Setters
}

一旦与“制作”中的“模型”建立了关系，就可以执行以下代码来获取结果：

Calendar cal = Calendar.getInstance();
// today 
Date toDate=cal.getTime(); 
cal.add( Calendar.DATE, -30 );
//date before 30 days
Date fromDate=cal.getTime();


Criteria criteria = session.createCriteria(Make.class , "m")
        .createAlias("models", "s")
        .add(Restrictions.between("s.modelCreationDate",  fromDate, toDate))
        // if the above condition dosen't give you exact result you may try following(2)
        // try gt or lt ... as needed 
        //.add(Restrictions.ge("publicationDate", fromDate)) 
        //.add(Restrictions.le("publicationDate", fromDate))
        .setResultTransformer(Criteria.DISTINCT_ROOT_ENTITY);

List<Make> ll2 = criteria.list();

Answer 2

对不起，我不知道为什么将日期声明为字符串：

私有字符串 modelCreationDate;

无论如何，我假定您将modelCreationDate声明为Date / LocalDate或类似的Type。我尚未测试代码，但希望以下代码可以解决您的问题。祝你好运！

SELECT COUNT(*) FROM parent WHERE Date1 <= DATEADD(DAY, -3, GETDATE())

Answer 3

除了user3169715's answer之外，我还可以使用查询来检索记录

Calendar cal = Calendar.getInstance();
Date toDate = cal.getTime();
cal.add(Calendar.DATE, -30);
Date fromDate = cal.getTime();

String hql = "SELECT make FROM Model m where m.modelCreationDate between :from_date and :to_date";
Query query = session.createQuery(hql);
query.setParameter("from_date", fromDate);
query.setParameter("to_date", toDate);

List results = query.list(); // Result list

依赖类的Hibernate CreateCriteria

3 个答案: