An alias is useful when we want a relationship between tables and also when we want to refer to a field of the child object using a field of the parent object. So, an alias works as a bridge between them and is also used to refer to a field.
Let's consider one scenario. We have an Employee and Department relationship where each employee has only one department, but each department can be used multiple times for different employees. Add the following code to the respective files:
Source file: Employee.java
@Entity
@Table
public class Employee{
@Id
@GeneratedValue
private long id;
@Column
private String name;
@ManyToOne
@JoinColumn
private Department department;
// getters and setters
}Source file: Department.java
@Entity
@Table
public class Department{
@Id
@GeneratedValue
private long id;
@Column
private String name;
// getters and setters
}