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

Comments

Post a Comment

Popular posts from this blog

STRUTS ACTION - AGGREGATING ACTIONS IN STRUTS

If you are a Struts developer then you might have experienced the pain of writing huge number of Action classes for your project. The latest version of struts provides classes using which you can aggregate a related set of actions into a single unified action. In this article we will see how to achieve this. Struts provides four important classes for this purpose. These classes are called as Dispatchers. The important Dispatchers that struts provides includes :   DispatchAction ,   ActionDispatcher   ,   LookupDispatchAction   and MappingDispatchAction . All these classes can be found in the package   org.apache.struts.actions . Let us look in to each of these in detail. Our examples use the simple CRUD actions. DispatchAction:   In this type of aggregation, the action class must extend DispatchAction class as shown. public final class CRUDDispatchAction extends DispatchAction { public ActionForward create(ActionMapping mapping, ActionForm form, HttpServletRequest reque
Read more

Servlets, JSP, Struts and MVC

Image
1.General Information about servlet: Servlet Request & Response Model: There are three different players in this picture: browser, web server, and servlet Container. In many cases, a web server and a servlet container are running in a same machine even in a single virtual machine. So they are not really distinguished in many cases. Anyway, the role of the web server is to receive HTTP request and then passes it to the web container or servlet container Which then creates Java objects that represent “HTTP request” and a “session” and then dispatches the request to the servlet by invoking service() method defined in the servlet.         The most common form of client requests are HTTP GET and HTTP POST requests. In the HTTP GET request, the user entered information is appended to the URL as a query string. In the HTTP POST request, on the other hand, the user entered information is sent as data. Servlet Classes and Interfaces: This picture shows important
Read more