JPA Criteria Having Clause

by Online Tutorials Library July 14, 2022

JPA Criteria Having clause

The HAVING clause is used with GROUP BY clause to filter the data in a table. In Criteria API, the having() method of Abstract interface is used to set the conditions on the grouped data.

Criteria HAVING Example

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

Now, follow the below steps to perform operations: –

Create an entity class names as StudentEntity.java under com.tutoraspire.jpa package. This class contains three attributes s_id, s_name and 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 created the basic entity class and mapped the configuration into persistence.xml file, we can perform the different types of HAVING operation. Here, we are grouping the number of student having age either equal or greater than 24.

StudentHaving.java

  package com.tutoraspire.jpa.jpql;  import com.tutoraspire.jpa.StudentEntity;  import javax.persistence.*;  import javax.persistence.criteria.*;    import java.util.*;  public class StudentHaving {      public static void main( String args[]) {           EntityManagerFactory emf = Persistence.createEntityManagerFactory( “Student_details” );        EntityManager em = emf.createEntityManager();        em.getTransaction().begin( );            CriteriaBuilder cb = em.getCriteriaBuilder();  CriteriaQuery<object>cq = cb.createQuery(Object[].class);  Root stud = cq.from(StudentEntity.class);    cq.multiselect(stud.get(“s_age”),cb.count(stud)).groupBy(stud.get(“s_age”)).having(cb.ge(stud.get(“s_age”), 24));         System.out.print(“s_age”);  System.out.println(“t Count”);  List<object>list = em.createQuery(cq).getResultList();  for(Object[] object : list){  System.out.println(object[0] + ” ” + object[1]);    }    em.getTransaction().commit();        em.close();        emf.close();     }  }</object>[]></object>[]>

Output:

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