Hibernate Avg() Function (Aggregate Functions)

In this section, we will show you, how to use the avg() 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 (avg() function) with their respective syntax.

avg( [ distinct | all ] object.property):

The avg() function aggregates the average value of the given column. 

Table Name: insurance

ID	insurance_name	invested_amount	investement_date
2	Life Insurance	25000	0000-00-00 00:00:00
1	Givan Dhara	20000	2007-07-30 17:29:05
3	Life Insurance	500	2005-10-15 00:00:00
4	Car Insurance	2500	2005-01-01 00:00:00
5	Dental Insurance	500	2004-01-01 00:00:00
6	Life Insurance	900	2003-01-01 00:00:00
7	Travel Insurance	2000	2005-02-02 00:00:00

Here is the java code to retrieve the average 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.cfg.Configuration; public class HibernateHQLAvgFunction {   /**  * @Vinod kumar  */   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 avg (investementAmount) from Insurance insurance";   Query query = sess.createQuery(SQL_QUERY);   List list = query.list();   System.out.println("Average of  Invested Amount: " + list.get(0));   }   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 avg(insurance0_.invested_amount) as col_0_0_ from insurance insurance0_ Average of Invested Amount: 7342.8571