JPA ORDER BY Clause

The ORDER BY clause is used to sort the data and arrange them either in ascending or descending order. The CriteriaQuery interface provides orderBy() method to define the type of ordering.

ORDER BY Example

Here, we will perform several ORDER BY operations on student table. Let us assume the table contains the following records: –

JPA ORDER BY Clause

Now, follow the below steps to perform operations: –

Create an entity class. Here, we created StudentEntity.java under com.tutoraspire.jpa package. This class contains three attributes s_id, s_name, s_age with all the required annotations.

StudentEntity.java

  package com.tutoraspire.jpa;  import javax.persistence.*;    @Entity  @Table(name=”student”)  public class StudentEntity {    @Id  private int s_id;  private String s_name;  private int s_age;    public StudentEntity(int s_id, String s_name, int s_age) {  super();  this.s_id = s_id;  this.s_name = s_name;  this.s_age = s_age;  }    public StudentEntity() {  super();  }    public int getS_id() {  return s_id;  }    public void setS_id(int s_id) {  this.s_id = s_id;  }    public String getS_name() {  return s_name;  }    public void setS_name(String s_name) {  this.s_name = s_name;  }    public int getS_age() {  return s_age;  }    public void setS_age(int s_age) {  this.s_age = s_age;  }    }  

Now, map the entity class and other databases confiuguration in Persistence.xml file.

Persistence.xml

  <persistence>  <persistence-unit name=”Student_details”>             <class>com.tutoraspire.jpa.StudentEntity</class>          <properties>           <property name=”javax.persistence.jdbc.driver” value=”com.mysql.jdbc.Driver”/>           <property name=”javax.persistence.jdbc.url” value=”jdbc:mysql://localhost:3306/studentdata”/>           <property name=”javax.persistence.jdbc.user” value=”root”/>           <property name=”javax.persistence.jdbc.password” value=””/>           <property name=”eclipselink.logging.level” value=”SEVERE”/>           <property name=”eclipselink.ddl-generation” value=”create-or-extend-tables”/>        </properties>             </persistence-unit>    </persistence>  

Once, we have created the basic entity class and mapped the configuration into persistence.xml file, we can perform the different types of select operations in the following ways: –

Sorting in ascending order

Asc.java

  package com.tutoraspire.jpa.jpql;  import com.tutoraspire.jpa.StudentEntity;  import javax.persistence.*;  import javax.persistence.criteria.*;    import java.util.*;  public class Asc {      public static void main( String args[]) {           EntityManagerFactory emf = Persistence.createEntityManagerFactory( “Student_details” );        EntityManager em = emf.createEntityManager();        em.getTransaction().begin( );        CriteriaBuilder cb=em.getCriteriaBuilder();        CriteriaQuery cq=cb.createQuery(StudentEntity.class);               Root stud=cq.from(StudentEntity.class);                        cq.orderBy(cb.asc(stud.get(“s_age”)));        CriteriaQuery select = cq.select(stud);        TypedQuery q = em.createQuery(select);        List list = q.getResultList();          System.out.print(“s_id”);       System.out.print(“t s_name”);       System.out.println(“t s_age”);                for(StudentEntity s:list)        {        System.out.print(s.getS_id());        System.out.print(“t”+s.getS_name());        System.out.println(“t”+s.getS_age());        }           em.getTransaction().commit();        em.close();        emf.close();     }  }  

output:

JPA ORDER BY Clause

Sorting in descending order

Desc.java

  package com.tutoraspire.jpa.jpql;  import com.tutoraspire.jpa.StudentEntity;  import javax.persistence.*;  import javax.persistence.criteria.*;    import java.util.*;  public class Desc {      public static void main( String args[]) {           EntityManagerFactory emf = Persistence.createEntityManagerFactory( “Student_details” );        EntityManager em = emf.createEntityManager();        em.getTransaction().begin( );        CriteriaBuilder cb=em.getCriteriaBuilder();        CriteriaQuery cq=cb.createQuery(StudentEntity.class);               Root stud=cq.from(StudentEntity.class);                        cq.orderBy(cb.desc(stud.get(“s_age”)));        CriteriaQuery select = cq.select(stud);        TypedQuery q = em.createQuery(select);        List list = q.getResultList();          System.out.print(“s_id”);       System.out.print(“t s_name”);       System.out.println(“t s_age”);                for(StudentEntity s:list)        {        System.out.print(s.getS_id());        System.out.print(“t”+s.getS_name());        System.out.println(“t”+s.getS_age());        }     em.getTransaction().commit();        em.close();        emf.close();     }  }  

output:

JPA ORDER BY Clause

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