JPA/Hibernate选择查询返回重复记录

Question

我有一个表,比如,具有ID,State和User_ID的Instrument作为列.

所以我有这个JPA查询返回所有具有匹配User_ID的乐器记录.

   query = manager.createQuery("SELECT instrument from Instrument instrument
             where instrument.User_ID=:User_ID",Instrument.class);
   query.setParameter("User_ID", User_ID);

   List<Instrument> instruments=  query.getResultList();

   for(Instrument instrument:instruments){
            System.out.println("Instrument ID  "+instrument.getID());
              // using sysout as it is not prod code yet
        }

它只返回重复的第一条记录,与匹配的记录一样多次.

11:13:01,703 INFO  [stdout] (http-/127.0.0.1:8080-1) Instrument ID   1
11:13:01,704 INFO  [stdout] (http-/127.0.0.1:8080-1) Instrument ID   1
11:13:01,704 INFO  [stdout] (http-/127.0.0.1:8080-1) Instrument ID   1

我在Db中有三个记录,仪器ID为1,2和3

我在hibernate上启用了show sql查询,查询在数据库上直接运行并返回不同的记录.

Hibernate查询:

    select instrumentjdo0_.User_ID as member_U1_0_, instrumentjdo0_.ID as ID2_0_, 
instrumentjdo0_.state as state4_0_ from instrument instrumentjdo0_ where instrumentjdo0_.User_ID=?

仪器实体

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;




@Entity
@Table(name = "instrument")
public class Instrument{

    @Id
    @Column(name="User_ID", length=9, unique=true, nullable=false)
    String user_ID;

    @Column(name="ID",nullable=false)
    String ID;


    @Column(name="state",nullable=false)
    String state;

    public String getID() {
        return ID;
    }

    public void setID(String ID) {
        this.ID = ID;
    }

    public String getUserID() {
        return user_ID;
    }

    public void setUserID(String userID) {
        this.user_ID = userID;
    }


    public String getState() {
        return state;
    }

    public void setState(String state) {
        this.state = state;
    }
}

不确定我错过了什么.

Answer 1

问题是,仪器实体中的错误列具有@ID分配给它的属性.

我删除它User_ID并添加到ID它,它工作正常.

Answer 2

我也遇到过同样的问题.对于联系表,我只将firstname列标记为@Id.并且表具有多个具有相同的行,firstname因为具有相同的第一行记录firstname在整个结果集中被复制.要解决此问题,我IdClass使用名字和姓氏作为id属性,并将其作为我的bean中的id类导入.由于firstname和lastname共同形成了独特的组合,它解决了我的问题.

Idclass 如下

public class ContactKey implements Serializable{

    protected String firstName;
    protected String lastName;

    public boolean equals(final Object inObject) {
        if (null != inObject) {
            if (inObject.getClass().equals(this.getClass())) {
                CqCamAdminKey siteKey = (CqCamAdminKey) inObject;
                return (null != this.getFirstName() && this.getFirstName().equals(siteKey.getFirstName()) && null != this.getLastName() && this.getLastName().equals(siteKey.getLastName()));
            }
        }
        return super.equals(inObject);
    }

    public int hashCode() {
        if (this.getFirstName() != null && this.getLastName() != null) {
            return this.getFirstName().hashCode() + this.getLastName().hashCode();
        }
        return super.hashCode();
    }
}

bean类如下

@IdClass(contactKey.class)
public abstract class CqCamAdminDataBean implements DataModelConstants{

    private static final long serialVersionUID = 7686374823515894764L;

    @Id
    @JsonIgnore
    @XmlTransient
    @Column(name = FIRST_NAME)
    protected String firstName;


    @Id
    @JsonIgnore
    @Column(name = LAST_NAME)
    protected String lastName;

}