java - 将 PostgreSQL Query 转换为对应的 Hibernate Query

Question

我需要为 PostgreSQL 查询提供相应的 Hibernate 查询。

这里是查询

select DATE(row_created) from DemoTable

其中 DATE 是 PostgreSQL 中的内置函数，row_created 是 DemoTable 中的列，数据类型为 timestamp without time zone.

这是我的 POJO 类

import java.util.ArrayList;
import java.util.Date;
import java.util.List;
import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.OneToMany;
import javax.persistence.Table;
import javax.persistence.Transient;
import javax.validation.constraints.NotNull;
@Entity
@Table(name = "candidate")
public class Candidates { 
    @Id
    @Column(name = "id")
    @GeneratedValue(strategy = GenerationType.AUTO)
    private int candidateId;

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

    @NotNull
    @Column(name = "mail_id")
    private String mailId;

    @NotNull
    @Column(name = "mobile_number")
    private String mobileNumber;

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

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

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

    @NotNull
    @Column(name = "notice_period")
    private String noticePeriod;

    @Column(name = "prefered_job_location")
    private String preferedJobLocation;

    @Column(name = "resume_filepath_name")
    private String resumeFilepathName;

    @Column(name = "primary_skill")
    private String primarySkill;

    @NotNull
    @Column(name = "is_active")
    private Short isActive;

    @NotNull
    @Column(name = "row_created")
    private Date rowCreated;

    @Column(name = "row_altered")
    private Date rowAltered;

    @NotNull
    @ManyToOne
    @JoinColumn(name="tracker_fk_id")
    private Tracker trackerFk;

}

任何人都可以帮助获得等效的 Hibernate 查询。

谢谢

Answer 1

您可以像这样创建一个查询:

//Select your object that you want
Query query = em.createNamedQuery("SELECT a FROM DemoTable a WHERE mycondition");

1-以防单例约会

//Get result list or a single result like what you want
DemoTableEntity myresult = (DemoTableEntity) query.getSingleResult();

//get the date from this result
Date mydate = myresult.getRowCreated();

2-以防获取日期列表

List<Date> listeDate = new ArrayList<>();

List<DemoTableEntity> list = query.getResultList();

for(DemoTableEntity ent : list){
   listeDate.add(ent.getRowCreated());
}

3-如果要获取一列的结果列表

Query query = em.createNamedQuery("SELECT a.rowAltered FROM Candidates a");
List<Date> dates = query.getResultList();

希望对您有所帮助。