Hibernate Select Query
This tutorial contain the explanation of Select clause.
Hibernate Select Clause :
The work of Select clause is to select whole database record or select the desired record under any condition .It gathers objects and properties then returns it in a query set.
In hibernate you can use native query or HQL to select records by using SELECT clause. For specific record selection use where clause.
Here we are taking example of employee. So for selecting records of employee table we write query as -
SELECT emp.name, emp.salary, emp.dateOfJoin from Employee emp
This is your select clause, picking the employee details as employee name, salary and date of join from Employee table.
package net.roseindia.main;
import java.util.*;
import net.roseindia.table.Employee;
import net.roseindia.util.HibernateUtil;
import org.hibernate.Criteria;
import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.criterion.Restrictions;
public class MainClass {
public static void main(String[] args) {
SessionFactory sessionFactory = HibernateUtil.getSessionFactory();
Session session = sessionFactory.openSession();
String hql="SELECT emp.name, emp.salary, emp.dateOfJoin from Employee emp";
Query query=session.createQuery(hql);
query.setResultTransformer(Criteria.ALIAS_TO_ENTITY_MAP);
List objectList = query.list();
Iterator iterator = objectList.iterator();
System.out.println("Employee Name \t Salary \t Date of Join");
while(iterator.hasNext()){
Map map = (Map)iterator.next();
System.out.print(map.get("0"));
System.out.print("\t\t"+map.get("1"));
System.out.print("\t\t"+map.get("2"));
System.out.println();
}
session.close();
}
}
Output:
Hibernate: select employee0_.name as col_0_0_, employee0_.salary as col_1_0_, employee0_.date_of_join as col_2_0_ from employee employee0_ Employee Name Salary Date of Join Mandy 20000 2010-03-12 00:00:00.0 Som 20000 1999-06-22 00:00:00.0 Mandy 15000 2003-12-23 00:00:00.0 Roxi 220000 2001-02-03 00:00:00.0 Rowdy 20000 2012-06-27 00:00:00.0