Java AnnotationException:引用dayHibernate的外键。。。列数错误。应该是3

我只想从两个表中从standard employees db MySQL获取数据：

EMPLOYEES {
   EMP_NO, -- PK
   BIRTH_DATE,
   ....
}

TITLES {
   EMP_NO, -- PK, and FK to EMPLOYEES
   TITLE, -- PK
   FROM_DATE, -- PK
   TO_DATE,
   ....
}

这是多个关键列：

@Embeddable
public class TitleId implements Serializable {
    @Column(name = "emp_no")
    private long empNumber;

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

    @Column(name = "from_date")
    private java.sql.Date fromDate;

// constructor, hascode, setter, getter
// ................

}

还有一些实体：

第一实体

@Entity(name = "Title")
@Table(name = "titles")
public class Title implements Serializable {

    @EmbeddedId
    private TitleId titleId;

    @Column(name = "to_date")
    private java.sql.Date toDate;

    @OneToMany(mappedBy = "title")
    private List<Employee> employees = new ArrayList<>();

// constructor, setter, getter

}

而雇员DAO是：

    List employees = session.createQuery("FROM Employee").list();
    for (Iterator iterator = employees.iterator(); iterator.hasNext();){
        Employee employee = (Employee) iterator.next();
        System.out.print("First Name: " + employee.getFirstName());
        System.out.print("  Last Name: " + employee.getLastName());
    }

当我试图获取这些数据时，还有一个例外

AnnotationException: A Foreign key refering dayHibernate.Title from dayHibernate.Employee has the wrong number of column. should be 3

---

如何从这两个表中获取数据并避免异常？请帮助我

在引用的实体上使用复合键时，不能将@JoinColumn与@ManyToOne一起使用。例外情况说明了一切，Employee试图仅使用emp_no引用Title，但复合键中还有两个字段

我认为这是整个实体模型的设计问题。由于TitleId包含雇员的主键，因此头衔实体不应与雇员建立多对一关系，但雇员应具有多个头衔

由于Emp_no位于复合密钥中，并且是一个外键，因此您应该能够使用@MapsId

这对我很有用：

雇员

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

    @Id
    @Column(name = "emp_no")
    private long empNo;

    @OneToMany(mappedBy="employee")
    private List<Title> titles = new ArrayList<>();

    ... }

头衔

---

将@JoinColumns添加到Employee表

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

    @Id
    @Column(name = "emp_no")
    private long empNo;

    @ManyToOne(optional = false)
      @JoinColumns ({
      @JoinColumn(name="emp_number", referencedColumnName = "emp_no"),
      @JoinColumn(name="title", referencedColumnName = "title"),
      @JoinColumn(name="from_date", referencedColumnName = "from_date")
    })
    private Title title;

 //   setter, getter, constructor, other coluns
}

---

我尝试注释Employee类中的多个JoinColumn注释和Title字段，并对Title类中的列表使用OneToMany MapsIdempNumber注释，但存在：org.hibernate.AnnotationException:未知实体名称：java.util.List另一种方法我尝试在Employee类中使用MapsIdempNumber注释，而不是JoinColumn注释，但存在SQLSyntaxErrorException:未知列“字段列表”中的“employee0\u0.title\u emp\u no”，请再次查看，如果你有time@ordenvall但当我试图从employee中的标题中获取数据时，有一个java.sql.SQLSyntaxErrorException:未知列'field list'中的'titles0.\uEmployee.\u emp.\u no'，我使用MySql测试数据库-感谢您的响应，但在'field list'@Vadimp'中有一个java.sql.sqlsyntaxerException:未知列'employee0..empNumber'，我更新了答案，referencedColumnName应该是实际的column。

@Embeddable
public class TitleId implements Serializable {

    private static final long serialVersionUID = 1L;

    @Column(name = "emp_no")
    private long empNumber;

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

    @Column(name = "from_date")
    private java.sql.Date fromDate;
}

@Entity(name = "Title")
@Table(name = "titles")
public class Title implements Serializable {

    @EmbeddedId
    private TitleId titleId;

    @Column(name = "to_date")
    private java.sql.Date toDate;

    @MapsId("empNumber")
    @JoinColumn(name = "emp_no")
    @ManyToOne
    private Employee employee;

}

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

    @Id
    @Column(name = "emp_no")
    private long empNo;

    @ManyToOne(optional = false)
      @JoinColumns ({
      @JoinColumn(name="emp_number", referencedColumnName = "emp_no"),
      @JoinColumn(name="title", referencedColumnName = "title"),
      @JoinColumn(name="from_date", referencedColumnName = "from_date")
    })
    private Title title;

 //   setter, getter, constructor, other coluns
}