Question

I am trying to learn Hibernate and I could create some simple CRUD operation using a Single Class and Single Table. I am just reading the Hibernate Doc and some online tutorial.

But I have a problem on how to define this relationship with two tables involved. I basically have an Employee table with this structure.

CREATE TABLE EMPLOYEE
(
 EMP_ID VARCHAR(10) NOT NULL,
 EMP_FIRST_NAME VARCHAR(30) NOT NULL,
 EMP_LAST_NAME VARCHAR(30) NOT NULL,
 STATUS_ID INT NOT NULL,
 PRIMARY KEY (EMP_ID)
);

The STATUS_ID field references another table. STATUS_DESC can either be ‘PERMANENT’, ‘CONTRACTUAL’, ‘ON-DEMAND’

CREATE TABLE EMP_STATUS
(
 STATUS_ID VARCHAR(10) NOT NULL,
 STATUS_DESC VARCHAR(100) ,
 PRIMARY KEY (STATUS_ID)
);

I am thinking of having an Entity class like this. Now my goal is to return list of Employee object with status, but I don’t know how to go about on doing this.

@Entity
public class Employee{
 //other private instance
 private EmployeeStatus empStatus;
 //getters and setters.
}

public class EmployeeStatus{
 private int statusID;
 private String statusDesc;
 //getters and setters
}

Answer 1

You want to know how to map it? ManyToOne?

Employee.java

@Entity
public class Employee{
   //other private instance

   @JoinColumn(name = "empStatus", referencedColumnName = "yourColName")
   @ManyToOne(optional = false)
   private EmployeeStatus empStatus;

   //getters and setters.
}

Dont forget to change “referencedColumnName” value…

EmployeeStatus.java

@Entity
public class EmployeeStatus{
   @Id //this is your pk?
   private int statusID;
   private String statusDesc;

   @OneToMany(cascade = CascadeType.ALL, mappedBy = "empStatus", fetch = FetchType.LAZY) //or EAGER
   private List<Employee> empList;

   //getters and setters
}