Hibernate和JPA ： 具有复合主键的表：自动增量问题

Question

我有这些实体：

@Entity
public class Carburant implements Serializable{
@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
@Column(name="id_carburant")
private long id;
private String nom;
private String description;
@JsonIgnore
@OneToMany(mappedBy="carburant")
private Set<HistCarb> stations ;
public Carburant() {
super();
}
}

2

@Entity
@Table(name="Station")
public class Station implements Serializable{
@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
@Column(name="id_station")
private long id ;
private String nom;
private String ville;
private String adresse;
@Transient
private boolean nul = false;
@JsonIgnore
@OneToMany(mappedBy="station")
private Set<HistCarb> historiques ;
public Station() {
super();
}
}

3

@Entity
public class HistCarb implements Serializable{
@Id
@Column(name="id",updatable=false,nullable=false)
@GeneratedValue(strategy=GenerationType.IDENTITY)
private long id;
private Date date;
private Integer prix;
@Id
@ManyToOne
@JoinColumn(name="id_station")
private Station station ;
@Id
@ManyToOne
@JoinColumn(name="id_carburant")
private Carburant carburant ;

public HistCarb() {
super();
}
}

类图：在此处输入图像描述

问题是：hibernate给我这个表HistCarb:的sql代码

create table HistCarb (
id bigint not null,
date datetime,
prix integer,
id_station bigint not null auto_increment,
id_carburant bigint not null,
primary key (id_station, id, id_carburant)
) engine=InnoDB

使用id_station-auto_increment，但我希望hibernate只生成列id作为auto_increment字段，正如我在实体3中实际提到的那样我希望有人能帮我解决这个问题。我没有为实体3使用嵌入式ID，我认为我们可以在没有嵌入式ID的情况下实现它，因为我发现它很难实现，当我试图在这种情况下使用嵌入式ID时，它会出现一些错误。

Answer 1

在HistCarb中，您在3个字段上有@Id，这就是您获得复合键的原因。从station和carburant中删除@Id，如下所示：

@Entity
public class HistCarb implements Serializable{
@Id
@Column(name="id",updatable=false,nullable=false)
@GeneratedValue(strategy=GenerationType.IDENTITY)
private long id;
private Date date;
private Integer prix;
@ManyToOne
@JoinColumn(name="id_station")
private Station station ;
@ManyToOne
@JoinColumn(name="id_carburant")
private Carburant carburant ;

public HistCarb() {
super();
}
}