Wednesday 24 August 2011

Max() Function

In this section, we will show you, how to use the Max() function. Hibernate supports multiple aggregate functions.

Hibernate Max() Function (Aggregate Functions)

In this section, we will show you, how to use the Max() function. Hibernate supports multiple aggregate functions. When they are used in HQL queries, they return an aggregate value ( such as avg(...), sum(...), min(...), max(...) , count(*), count(...), count(distinct ...), count(all...) ) calculated from property values of all objects satisfying other query criteria. 
Following is a aggregate function (max() function) with their respective syntax.
max( [ distinct | all ] object.property)
The Max() function aggregates the maximum value of the given column. 
Table Name: insurance









IDinsurance_nameinvested_amountinvestement_date
2Life Insurance250000000-00-00 00:00:00
1Givan Dhara20000 2007-07-30 17:29:05
3Life Insurance 5002005-10-15 00:00:00
4Car Insurance  25002005-01-01 00:00:00
5Dental Insurance5002004-01-01 00:00:00
Life Insurance9002003-01-01 00:00:00
Travel Insurance 2000 2005-02-02 00:00:00
Here is the java code to retrieve the maximum value of "invested_amount" column 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 HibernateHQLMaxFunction {

  /**
 * mail_mevinod@yahoo.co.in
 */
  public static void main(String[] args) {
  // TODO Auto-generated method stub

  Session sess = null;
  try {
  SessionFactory fact = new 
Configuration
().configure().buildSessionFactory();
  sess = fact.openSession();
  String SQL_QUERY = "select
max(investementAmount)from Insurance insurance"
;
  Query query = sess.createQuery(SQL_QUERY);
  List list = query.list();
  System.out.println("Max
Invested Amount: " 
+ list.get(0))
  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 max(insurance0_.invested_amount) as col_0_0_ from insurance insurance0_
Max Invested Amount: 25000

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