我们如何在 Hibernate 中按日期对结果进行排序？

Question

我正在使用 Hibernate 从数据库中获取 JSON 对象。我希望 JSON 对象应该包含最近创建的 VGI 中仅有的前两个的所有详细信息。但是我不知道如何限制结果集，然后在不使用 HQL 查询时根据创建日期进行排序。它正在从 MySQL 数据库中获取所有详细信息。

import java.util.Date;
import java.util.List;

import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.OneToMany;
import javax.persistence.OneToOne;
import javax.persistence.Table;

@Entity
@Table(name = "vgi", catalog = "coworkee5")
public class VGI {
@ManyToOne
@JoinColumn(name = "employee_id", referencedColumnName = "id", insertable = false, updatable = false)
private Employees employees;

public Employees getEmployees() {
    return employees;
}

public void setEmployees(Employees employees) {
    this.employees = employees;
}

@OneToMany(cascade = CascadeType.ALL, targetEntity = VgiGoals.class, mappedBy = "vgi")
private List<VgiGoals> vgiGoals;

public List<VgiGoals> getVgiGoals() {
    return vgiGoals;
}

public void setVgi_goals(List<VgiGoals> vgiGoals) {
    this.vgiGoals = vgiGoals;
}

public VGI() {
}

@Id
@Column(name = "id")
private String id;
@Column(name = "title")
private String vgi;
@Column(name = "employee_id")
private String employee_id;
@Column(name = "created_on")
private String created;

public String getId() {
    return id;
}

public void setId(String id) {
    this.id = id;
}

public String getvgi() {
    return vgi;
}

public void setvgi(String vgi) {
    this.vgi = vgi;
}

public String getEmployee_id() {
    return employee_id;
}

public void setEmployee_id(String employee_id) {
    this.employee_id = employee_id;
}


public String getCreated() {
    return created;
}

public void setCreated(String created) {
    this.created = created;
}

}

Answer 1

添加@OrderBy 注释以进行如下排序。

@OneToMany(cascade = CascadeType.ALL, targetEntity = VgiGoals.class, mappedBy = "vgi")
@OrderBy("createdOn DESC")
private List<VgiGoals> vgiGoals;

注意：将 createdOn 替换为 VgiGoals 类中的日期字段。

并且在查询中限制使用以下方法。

query.setFirstResult(1).setMaxResults(10);