Named query is a concept of using queries by name. First a query is defined and a name is assigned to it. Then it can be used anywhere by this alias name.
Syntax of hibernate named query using annotation:
@NamedQueries({ @NamedQuery(name = " queryName ", query = " queryString ") }) |
How to call a named query?
We can call the named query by getNamedQuery() method of Session interface.
Query query = session.getNamedQuery("queryName");
Example:
Student.java
import javax.persistence.Column; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.Id; import javax.persistence.NamedQueries; import javax.persistence.NamedQuery; import javax.persistence.Table; /** * This class represents a persistent class for Student. * @author w3schools */ @NamedQueries( { @NamedQuery( name = "getStudentByRollNo", query = "from Student where rollNo = :rollNo" ) } ) @Entity @Table(name= "STUDENT") public class Student { //data members private int studentId; private String firstName; private String lastName; private String className; private String rollNo; private int age; //no-argument constructor public Student(){ } //getter and setter methods @Id @GeneratedValue @Column(name = "Student_Id", unique = true, nullable = false) public int getStudentId() { return studentId; } public void setStudentId(int studentId) { this.studentId = studentId; } @Column(name = "First_Name") public String getFirstName() { return firstName; } public void setFirstName(String firstName) { this.firstName = firstName; } @Column(name = "Last_Name") public String getLastName() { return lastName; } public void setLastName(String lastName) { this.lastName = lastName; } @Column(name = "Class") public String getClassName() { return className; } public void setClassName(String className) { this.className = className; } @Column(name = "RollNo") public String getRollNo() { return rollNo; } public void setRollNo(String rollNo) { this.rollNo = rollNo; } @Column(name = "Age") public int getAge() { return age; } public void setAge(int age) { this.age = age; } } |
hibernate.cfg.xml
<?xml version='1.0' encoding='UTF-8'?> <!DOCTYPE hibernate-configuration SYSTEM "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd"> <hibernate-configuration> <session-factory> <property name="dialect"> org.hibernate.dialect.OracleDialect </property> <property name="connection.url"> jdbc:oracle:thin:@localhost:1521:XE </property> <property name="connection.username"> system </property> <property name="connection.password"> oracle </property> <property name="connection.driver_class"> oracle.jdbc.driver.OracleDriver </property> <property name="hbm2ddl.auto"> update </property> <property name="show_sql"> true </property> <mapping class="com.w3schools.business.Student"/> </session-factory> </hibernate-configuration> |
HibernateUtil.java
import org.hibernate.SessionFactory; import org.hibernate.cfg.Configuration; /** * This is a utility class for getting the hibernate session object. * @author w3schools */ public class HibernateUtil { private static final SessionFactory sessionFactory = buildSessionFactory(); private static SessionFactory buildSessionFactory() { SessionFactory sessionFactory = null; try { //Create the configuration object. Configuration configuration = new Configuration(); //Initialize the configuration object //with the configuration file data configuration.configure("hibernate.cfg.xml"); // Get the SessionFactory object from configuration. sessionFactory = configuration.buildSessionFactory(); } catch (Exception e) { e.printStackTrace(); } return sessionFactory; } public static SessionFactory getSessionFactory() { return sessionFactory; } } |
HibernateTest.java
import java.util.List; import org.hibernate.Query; import org.hibernate.Session; import com.w3schools.persistence.HibernateUtil; /** * This class is used for the hibernate operations. * @author w3schools */ public class HibernateTest { public static void main(String args[]){ //Create the student object. Student student = new Student(); //Setting the object properties. student.setFirstName("Sunil"); student.setLastName("Kunar"); student.setClassName("MCA final"); student.setRollNo("MCA/07/15"); student.setAge(27); //Get the session object. Session session = HibernateUtil.getSessionFactory().openSession(); //Start hibernate transaction. session.beginTransaction(); //Persist the student object. session.save(student); //Commit hibernate transaction. session.getTransaction().commit(); //select a student record using named query Query query = session.getNamedQuery("getStudentByRollNo"); query.setString("rollNo", "MCA/07/15"); List<Student> stuList = (List<Student>) query.list(); for(Student stu : stuList){ System.out.println("First Name: " + stu.getFirstName()); System.out.println("Last Name: " + stu.getLastName()); System.out.println("Class: " + stu.getClassName()); System.out.println("RollNo: " + stu.getRollNo()); System.out.println("Age: " + stu.getAge()); } //Close hibernate session. session.close(); } } |
Output:
Hibernate: select hibernate_sequence.nextval from dual Hibernate: insert into Student (First_Name, Last_Name, Class, RollNo, Age, Student_Id) values (?, ?, ?, ?, ?, ?) Hibernate: select student0_.Student_Id as Student1_0_, student0_.First_Name as First2_0_, student0_.Last_Name as Last3_0_, student0_.Class as Class0_, student0_.RollNo as RollNo0_, student0_.Age as Age0_ from Student student0_ where student0_.RollNo=? First Name: Sunil Last Name: Kunar Class: MCA final RollNo: MCA/07/15 Age: 27 |