Hibernate One to Many

File 1: Student.java

Code:

package test
import java.util.Set;
import javax.persistence.*;
@Entity
@Table(name = "Student")
public class Student {
@Id
@GeneratedValue
@Column(name = "S_id")
private int id;
@Column(name = "S_name")
private String Name;
@Column(name = "S_phno")
private String Phone;
@OneToMany(mappedBy = "Student", cascade = CascadeType.ALL)
private Set marksDetails;
public Student() { }
public int getId() {
return S_id;
}
public void setId(long S_id)  {
this.S_id = S_id;
}
public String getName() {
return Name;
}
public void setName(String Name) {
this.Name = Name;
}
public String getPhone() {
return phone;
}
public void setPhone(String phone) {
this.phone = phone;
}
public Set getMarksDetails() {
return marksDetails;
}
public void setMarksDetails(Set marksDetails) {
this.marksDetails = marksDetails;
}
}

File2: Marks.java

Code:

package test;
import javax.persistence.*;
@Entity
@Table(name = "Marks")
public class Marks {
@Id
@GeneratedValue
@Column(name = "M_testid")
private int M_testid;
@Column(name = "M_marks")
private String M_marks;
@ManyToOne
@JoinColumn(name = "S_id")
private Student student;
public Marks() { }
public int getTestId() {
return M_testid;
}
public void setTestId(int M_testid) {
this.M_testid = M_testid;
}
public String getMarks() {
return M_marks;
}
public void setMarks(String M_marks) {
this.M_marks = M_marks;
}
public Student getStudent() {
return student;
}
public void setStudent(Student student) {
this.student = student;
}
}

File 3: Test.java

Code:

package test;
import org.hibernate.*;
public class Test {
static Session sO;
static SessionFactory sF;
private static SessionFactory buildSessionFactory() {
Configuration cO = new Configuration();
cO.configure("hibernate.cfg.xml");
ServiceRegistry sRO = new StandardServiceRegistryBuilder().applySettings(cO.getProperties()).build();
sFO = cO.buildSessionFactory(sRO);
return sFO;
}
public static void main(String[] args) {
System.out.println("...Example of hibernate one to many mapping...");
try {
sO = buildSessionFactory().openSession();
sO.beginTransaction();
Student studentObj = new Student("Name1", "0123456789");
sessionObj.save(studentObj);
Marks mObj = new Marks ("20", "90");
mObj.setStudent(studentObj);
sO.save(mObj);
Marks mObj = new Marks ("10", "100");
mObj.setStudent(studentObj);
sO.save(mObj);
sO.getTransaction().commit();
System.out.println("\n...Records successfully registered in the database...");
} catch(Exception sqlException) {
if(null != sO.getTransaction()) {
System.out.println("\n.......error......");
sO.getTransaction().rollback();
}
sqlException.printStackTrace();
} finally {
if(sO != null) {
sO.close();
}
}
}
}

Output:

Conclusion

Hibernate is a model to maintain object relations from front end applications developed on java to back end databases. One of the important relation types we have often worked on in databases directly is “One to Many”. It has become easy to create “One to Many” relations in tables using hibernate one to many mapping annotations. It is a clean and clutter-free method of working with database-intensive applications. It helps developers to focus on writing business logic independent of any database beneath. It is definitely one of the cool tools in the java world to work on databases.

Recommended Articles

This is a guide to Hibernate One to Many. Here we discuss the introduction; how does a “one to many” relationship work in hibernate? and example. You may also have a look at the following articles to learn more –

1. Hibernate Named Query
2. Caching in Hibernate
3. Hibernate Annotations
4. Hibernate Architecture