java - Create and populate child table from Parent table using Hibernate Annotation

Question

I need to create a table EMPLOYEE_REMARK from a table EMPLOYEE. And need to do it with Annotation Hibernate.

EMPLOYEE

EMP_ID, EMP_FNAME, EMP_LNAME

EMPLOYEE_REMARK

EMP_REMARK_ID, EMP_ID, REMARK

it will be a OnetoOne relationship i.e, for each EMP_ID there will be one REMARK. REMARK could be null.

please help me with the solution... Can it be done by creating one class from employee and populate the EMPLOYEE_REMARK from it???

Answer 1

Basically here is the way of doing what you want.

Employee

@Entity
@Table(name = "EMPLOYEE")
public class Employee implements Serializable {

    @Id
    @Column(name = "EMP_ID")
    private Long id;
    @Column(name = "EMP_FNAME")
    private String firstName;
    @Column(name = "EMP_LNAME")
    private String lastName;
    @OneToOne(mappedBy = "employee", cascade = CascadeType.ALL,
    orphanRemoval = true)
    private EmployeeRemark employeeRemark;

    public void setRemark(String remark) {
        this.employeeRemark = new EmployeeRemark();
        this.employeeRemark.setRemark(remark);
        this.employeeRemark.setEmployee(this);
    }

    public String getRemark() {
        return employeeRemark == null ? null : employeeRemark.getRemark();
    }

    //getters and setters
}

Employee Remark

@Entity
@Table(name = "EMPLOYEE_REMARK")
public class EmployeeRemark implements Serializable {

    @Id
    @Column(name = "EMP_REMARK_ID")
    private Long id;
    @OneToOne
    @JoinColumn(name = "EMP_ID")
    private Employee employee;
    @Column(name = "REMARK")
    private String remark;

    //getters and setters
}

When saving employee, just call save on employee. EmployeeRemark will cascade to all operations and will be removed along with employee or if it become an orphan in other way.