Hibernate Count Query


In this section we will show you, how to use the Count Query. Hibernate supports multiple aggregate functions. when they are used in HQL queries, they return an aggregate value (such as sum, average, and count) calculated from property values of all objects satisfying other query criteria. These functions can be used along with the distinct andall options, to return aggregate values calculated from only distinct values and all values (except null values), respectively. Following is a list of aggregate functions with their respective syntax; all of them are self-explanatory.
count( [ distinct | all ] object | object.property )
count(*) (equivalent to count(all ...), counts null values also)
sum ( [ distinct | all ] object.property)
avg( [ distinct | all ] object.property)
max( [ distinct | all ] object.property)
min( [ distinct | all ] object.property)
Here is the java code for counting the records from insurance table:
package roseindia.tutorial.hibernate;

import java.util.Iterator;
import java.util.List;

import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;

public class HibernateHQLCountFunctions {

  /**
 * 
 */
  public static void main(String[] args) {
  // TODO Auto-generated method stub

  Session sess = null;
  int count = 0;
  try {
  SessionFactory fact = new 
Configuration().configure()
.buildSessionFactory();
  sess = fact.openSession();
  String SQL_QUERY = "select 
count(*)from Insurance insurance group by 
insurance.lngInsuranceId";
  Query query = 
sess.createQuery(SQL_QUERY);
  for (Iterator it 
= query.iterate(); it.hasNext();) {
  it.next();
  count++;
  }
  System.out.println("
Total rows: " + count);
  sess.close();
  }
  catch(Exception e){
  System.out.println
(e.getMessage());
  }
  }

}

Output:
log4j:WARN No appenders could be found for logger (org.hibernate.cfg.Environment).
log4j:WARN Please initialize the log4j system properly.
Hibernate: select count(*) as col_0_0_ from insurance insurance0_ group by insurance0_.ID
Total rows: 6

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