java - Hibernate/JPA 自动创建外键而不是在多对一关联中使用现有的外键

Question

我使用:

• SpringBoot 1.5.1
• MariaDB/MySQL 10.1.14/15.1
• org.hibernate.dialect.MySQL5Dialect
• Hibernate5(默认为 SpringBoot)

这是 SQL 表定义:

CREATE TABLE salaries (
emp_no      BIGINT          NOT NULL,
salary      BIGINT          NOT NULL,
from_date   DATETIME        NOT NULL,
to_date     DATETIME        NOT NULL,
FOREIGN KEY (emp_no) REFERENCES employees (emp_no),
PRIMARY KEY (emp_no, from_date)
) 

这是关联多边上的实体(使用嵌入式 id):

@Entity
@Table(name = "salaries")
public class Salary {

    @EmbeddedId
    private EmpIdFromDatePK empId;

    @Column(name = "to_date", columnDefinition = "DATETIME")
    @Temporal(TemporalType.TIMESTAMP)
    private Date toDate;

    @Column(name = "salary")
    private Long salary;

    @ManyToOne(fetch = FetchType.LAZY)
    @Fetch(FetchMode.JOIN)
    @MapsId("empId")
    @JoinColumns({@JoinColumn(foreignKey = @ForeignKey(name = "salaries_ibfk_1"), name = "emp_no", referencedColumnName = "emp_no")})
    private Employee employee;

    public Salary() {
        super();
    }

    //...
}

关键类:

@Embeddable
public class EmpIdFromDatePK implements Serializable {

    @Column(name = "emp_no")
    private Long empId;

    @Column(name = "from_date", columnDefinition = "DATETIME")
    @Temporal(TemporalType.TIMESTAMP)
    private Date fromDate;

    public EmpIdFromDatePK() {
        super();
    }

    //....
} 

以及关联一侧的实体:

@Entity
@Table(name = "employees")
public class Employee {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "emp_no")
    private Long empId;

    //...

    @OneToMany(mappedBy = "employee")
    private List<Salary> salaryList;

    //...
}

问题:当我使用 ManyToOne 关联时(例如，在员工与工资记录关联的选择中)，在数据库中创建了第二个外键:

CONSTRAINT `FKjojacp79fphmajxrdll8fvf5o` FOREIGN KEY (`emp_no`) REFERENCES `employees` (`emp_no`),
CONSTRAINT `salaries_ibfk_1` FOREIGN KEY (`emp_no`) REFERENCES `employees` (`emp_no`)

问题:如何避免这种行为？

提前致谢

Answer 1

你能试试:

@JoinColumn(name="emp_no", referencedColumnName="emp_no")
@ForeignKey(name="salaries_ibfk_1")

?