Suppose there are two classes Employee and Address. To apply the one-to-one relationship from Employee object to multiple Address objects.

• Create the Project directory structure.

• Create the Persistence classes.

Employee.java [java]package com.itoolsinfo; import java.util.Set; public class Employee { private int id; private String name; private Set address; public int getId() { return id; } public void setId(int id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public Set getAddress() { return address; } public void setAddress(Set address) { this.address = address; } } [/java] Here the developer created the class Employee with the variables name and address, set and get methods are used on the variables. Set and Get methods are a pattern of data encapsulation. Instead of accessing class member variables directly, one can define get methods to access these variables, and set methods to modify them. Address.java [java]package com.itoolsinfo; public class Address { private int streetNumber; public int getStreetNumber() { return streetNumber; } public void setStreetNumber(int streetNumber) { this.streetNumber = streetNumber; } private String city, village, street; public String getCity() { return city; } public void setCity(String city) { this.city = city; } public String getVillage() { return village; } public void setVillage(String village) { this.village = village; } public String getStreet() { return street; } public void setStreet(String street) { this.street = street; } } [/java] Here the developer created the class Address with their variables such as streetNumber, city, village. Set and Get operations were performed on this variables.

• Map all POJO classes in mapping file that is employee.hbm.xml.

[xml]<?xml version='1.0' encoding='UTF-8'?> <!DOCTYPE hibernate-mapping PUBLIC “-//Hibernate/Hibernate Mapping DTD 3.0//EN” “http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd”> <hibernate-mapping> <class name=”com.itoolsinfo.Employee” table=”employee5”> <id name=”id” column=”id”> <generator class=”increment”></generator> </id> <property name=”name” length=”14”/> <set name=”address” cascade=”all”> <key column=”eid”/> <one-to-many class=”com.itoolsinfo.Address”/> </set> </class> <class name=”com.itoolsinfo.Address”table=”address8” > <id name=”streetNumber”> </id> <property name=”village” length=”14”/> <property name=”street”length=”14”/> <property name=”city” length=”14”></property> </class> </hibernate-mapping> [/xml]

• Configure the mapping file in Configuration file.

hibernate.cfg.xml [xml] <?xml version='1.0' encoding='UTF-8'?> <!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd"> <hibernate-configuration> <session-factory> <property name="connection.driver_class">oracle.jdbc.driver.OracleDriver</property> <property name="connection.url">jdbc:oracle:thin:@localhost:1521:XE</property> <property name="connection.username">system</property> <property name="connection.password">system</property> <property name="dialect">org.hibernate.dialect.Oracle10gDialect</property> <property name="hibernate.hbm2ddl.auto">create</property> <property name="show_sql">true</property> <mapping resource="employee.hbm.xml"/> </session-factory> </hibernate-configuration> [/xml]

• Create the SPLessons class and store the POJO class objects to perform database operations.

SPLessons.java [java]package com.itoolsinfo; import java.util.HashSet; import java.util.Set; import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.Transaction; import org.hibernate.cfg.Configuration; public class SPLessons { public static void main(String args[]) { SessionFactory factory=new Configuration().configure("hibernate.cfg.xml").buildSessionFactory(); Session session=factory.openSession(); // To insert parent Employee class property values. Employee employee=new Employee(); employee.setId(2); employee.setName(" jhosf " ); // To insert multiple Address class object values. Address address= new Address(); address.setStreetNumber(330); address.setStreet("Hariharapuram"); address.setVillage("BNReddy nagar"); address.setCity("LB nagar"); Address address1= new Address(); address1.setStreetNumber(314); address1.setStreet("yousufguda"); address1.setVillage("Ameerpet"); address1.setCity("Hyderabad"); // To add the address class objects in collection variable. Set <Address> set=new HashSet <Address>(); set.add(address); set.add(address1); // To set the collection variable to Employee class object. employee.setAddress(set); Transaction transaction=session.beginTransaction(); session.save(employee); transaction.commit(); session.close(); } } [/java] Here the developer created the class SPLessons to perform database operations as mentioned in the comments of the code.

• See the output in command prompt.

• See the output in database table using following command.

[sql]select * from employee;[/sql] [sql]select * from address;[/sql]

Suppose there are two classes Employee and Address. Apply one-to-one relationship from Employee object to multiple Address objects. Using the List type, add the index column in table.

• Create the Project directory structure.

• Create the Persistence classes.

Employee.java [java]package com.itoolsinfo; import java.util.List; public class Employee { private int id; private String name; private List address; public List getAddress() { return address; } public void setAddress(List address) { this.address = address; } public int getId() { return id; } public void setId(int id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } } [/java] Here created the class Employee with variables name and address, where set and get methods are used to perform action on this variables. Address.java [java]package com.itoolsinfo; public class Address { private int streetNumber; public int getStreetNumber() { return streetNumber; } public void setStreetNumber(int streetNumber) { this.streetNumber = streetNumber; } private String city, village, street; public String getCity() { return city; } public void setCity(String city) { this.city = city; } public String getVillage() { return village; } public void setVillage(String village) { this.village = village; } public String getStreet() { return street; } public void setStreet(String street) { this.street = street; } } [/java] Here the developer created the class Address with their variables such as streetNumber, city, village. Set and Get operations were performed on this variables.

• Map the POJO classes in mapping file that is employee.hbm.xml.

[xml]<?xml version='1.0' encoding='UTF-8'?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN""http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"> <hibernate-mapping> <hibernate-mapping> <class name="com.itoolsinfo.Employee"table="employee"> <id name="id" column="id"> <generator class="increment"></generator> </id> <property name="name" length="14"/> <list name="address" cascade="all"> <key column="eid"/> <index column="type"/> <one-to-many class="com.itoolsinfo.Address"/> </list> </class> <class name="com.itoolsinfo.Address" table="address" > <id name="streetNumber"/> <property name="village" length="14"> <property name="street" length="14"> <property name="city" length="14"></property> </class> /hibernate-mapping [/xml]

• Configure the mapping file in Configuration file.

hibernate.cfg.xml [xml] <?xml version='1.0' encoding='UTF-8'?> <!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd"> <hibernate-configuration> <session-factory> <property name="connection.driver_class">oracle.jdbc.driver.OracleDriver</property> <property name="connection.url">jdbc:oracle:thin:@localhost:1521:XE</property> <property name="connection.username">system</property> <property name="connection.password">system</property> <property name="dialect">org.hibernate.dialect.Oracle10gDialect</property> <property name="hibernate.hbm2ddl.auto">create</property> <property name="show_sql">true</property> <mapping resource="employee.hbm.xml"/> </session-factory> </hibernate-configuration> [/xml]

• Create the SPLessons class and store the POJO class objects to perform the Database operations.

SPLessons.java [java]package com.itoolsinfo; import java.util.ArrayList; import java.util.List; import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.Transaction; import org.hibernate.cfg.Configuration; public class SPLessons { public static void main(String args[]) { SessionFactory factory=new Configuration().configure("hibernate.cfg.xml").buildSessionFactory(); Session session=factory.openSession(); // To insert parent Employee class property values. Employee employee=new Employee(); employee.setId(1); employee.setName(" joshaf " ); Employee employee1=new Employee(); employee1.setId(2); employee1.setName(" jhon " ); // To insert multiple Address class object values. Address address= new Address(); address.setStreetNumber(330); address.setStreet("Hariharapuram"); address.setVillage("BNReddy nagar"); address.setCity("LB nagar"); Address address1= new Address(); address1.setStreetNumber(314); address1.setStreet("yousufguda"); address1.setVillage("Ameerpet"); address1.setCity("Hyderabad"); // To add the address class objects in collection variable. List <Address> list=new ArrayList <Address>(); list.add(address); List <Address> list1=new ArrayList <Address>(); list1.add(address1); // To set the collection variable to Employee class object. employee.setAddress(list); employee1.setAddress(list1); Transaction transaction=session.beginTransaction(); // To save the all employee class objects into the session object. session.save(employee); session.save(employee1); transaction.commit(); session.close(); } } [/java] SPLessons class is used to perform database operations as mentioned in the comments of the code.

• See the Output in command prompot.

• See the Output in Database table using following command.

[sql]select * from employee;[/sql] [sql]select * from address;[/sql]

In One-to-many relationship two annotations are used in Parent class. 1. @OneToMany(targetEntity="child class object of class",cascade=CasecadeType.ALL) It indicates mapping of child class object to Parent class object. 2. @JoinColumn(name="primary key column", name="foreign key column") Used to map the primary column in two tables. If there are two classes Employee and Address and want to apply one-to-one relationship from Employee object to multiple Address objects using Annotations and using Primary key column is id,

• Create the Project directory structure.

• Create the persistence classes.

Employee.java [java]package com.itoolsinfo; import java.util.Set; import javax.persistence.CascadeType; import javax.persistence.Column; import javax.persistence.Entity; import javax.persistence.Id; import javax.persistence.JoinColumn; import javax.persistence.OneToMany; import javax.persistence.Table; @Entity @Table(name="employee") public class Employee { @Id private int id; @Column(name="name") private String name; @OneToMany(targetEntity=Address.class,cascade=CascadeType.ALL) @JoinColumn(name="eid") private Set address; public int getId() { return id; } public void setId(int id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public Set getAddress() { return address; } public void setAddress(Set address) { this.address = address; } } [/java] Here the developer explained the code with same example, but here used annotaions, the purpose of annotation is to reduce the code. The @Table comment permits you to indicate the points of interest of the table that will be utilized to hold on the element in the database. The @Table explanation gives four traits, permitting you to abrogate the name of the table, its inventory, and its composition, and uphold exceptional imperatives on sections in the table. Address.java [java]package com.itoolsinfo; import javax.persistence.Column; import javax.persistence.Entity; import javax.persistence.Id; import javax.persistence.Table; @Entity @Table(name="address") public class Address { @Id private int streetNumber; public void setStreetNumber(int streetNumber) { this.streetNumber = streetNumber; } public int getStreetNumber() { return streetNumber; } public void setStreetNumber1(int streetNumber) { this.streetNumber = streetNumber; } @Column(name="street") private String street; @Column(name="village") private String village; @Column(name="city") private String city; /*public int getId() { return id; } public void setId(int id) { this.id = id; }*/ public String getCity() { return city; } public void setCity(String city) { this.city = city; } public String getVillage() { return village; } public void setVillage(String village) { this.village = village; } public String getStreet() { return street; } public void setStreet(String street) { this.street = street; } } [/java] Every element bean will have an essential key, which you comment on the class with the @Id comment. The essential key can be a solitary field or a mix of different fields relying upon your table structure. As a matter of course, the @Id comment will naturally decide the most suitable essential key era technique to be utilized however you can abrogate this by applying the @GeneratedValue explanation which takes two parameters system and generator

• Configure all classes in Configuration file.

hibernate.cfg.xml [xml] <?xml version='1.0' encoding='UTF-8'?> <!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd"> <hibernate-configuration> <session-factory> <property name="connection.driver_class">oracle.jdbc.driver.OracleDriver</property> <property name="connection.url">jdbc:oracle:thin:@localhost:1521:XE</property> <property name="connection.username">system</property> <property name="connection.password">system</property> <property name="dialect">org.hibernate.dialect.Oracle10gDialect</property> <property name="hibernate.hbm2ddl.auto">create</property> <property name="show_sql">true</property> <mapping resource="employee.hbm.xml"/> </session-factory> </hibernate-configuration> [/xml]

• Create the SPLessons class and store the POJO class objects to perform database operations.

SPLessons.java [java]package com.itoolsinfo; import java.util.HashSet; import java.util.Set; import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.Transaction; import org.hibernate.cfg.Configuration; public class SPLessons { public static void main(String args[]) { SessionFactory factory=new Configuration().configure("hibernate.cfg.xml").buildSessionFactory(); Session session=factory.openSession(); // To insert parent Employee class property values. Employee employee=new Employee(); employee.setId(2); employee.setName(" jhosf " ); // To insert multiple Address class object values. Address address= new Address(); address.setStreetNumber(330); address.setStreet("Hariharapuram"); address.setVillage("BNReddy nagar"); address.setCity("LB nagar"); Address address1= new Address(); address1.setStreetNumber(314); address1.setStreet("yousufguda"); address1.setVillage("Ameerpet"); address1.setCity("Hyderabad"); // To add the address class objects in collection variable. Set <Address> set=new HashSet <Address>(); set.add(address); set.add(address1); // To set the collection variable to Employee class object. employee.setAddress(set); Transaction transaction=session.beginTransaction(); session.save(employee); transaction.commit(); session.close(); } } [/java]

• See the output in command prompot.

• See the output in database table using following command.

[sql]select * from employee;[/sql] [sql]select * from address;[/sql]