how to fetch data from database in Hibernate

Question

This is my class to fetch data from database  package com javatpoint mypackage   import org hibernate Query  import org hibernate Session  import org hibernate SessionFactory  import org hibernate Transaction  import org hibernate cfg Configuration  import org hibernate mapping List   public class retrive       public static void main String args              Configuration cfg   new Configuration            cfg configure  hibernate cfg xml      populates the data of the                                                configuration file             creating seession factory object         SessionFactory factory   cfg buildSessionFactory                creating session object         Session session   factory openSession                creating transaction object         Transaction t   session beginTransaction             Query query   session createQuery  from EMPLOYEE            java util List list   query list            System out println list           t commit            session close              This is my Emplouyee hbm xml file     lt  xml version  1 0   gt   lt  DOCTYPE hibernate-mapping PUBLIC  -  Hibernate Hibernate Mapping DTD 3 0  EN                        http   hibernate sourceforge net hibernate-mapping-3 0 dtd  gt   lt  -- Generated 5 Dec  2013 12 09 18 PM by Hibernate Tools 3 4 0 CR1 -- gt   lt hibernate-mapping default-lazy  false  gt       lt class name  com javatpoint mypackage Employee  table  EMPLOYEE  gt           lt id name  id  type  int  gt               lt column name  ID    gt               lt generator class  assigned    gt           lt  id gt           lt property generated  never  lazy  false  name  firstName              type  java lang String  gt               lt column name  FIRSTNAME    gt           lt  property gt           lt property generated  never  lazy  false  name  lastName              type  java lang String  gt               lt column name  LASTNAME    gt           lt  property gt       lt  class gt   lt  hibernate-mapping gt    when i run this Program then following Exception come please help me how to Fix it i am new in Hibernate and trying learn but am stuck   Exception in thread  main  org hibernate hql ast QuerySyntaxException              EMPLOYEE is not mapped  from EMPLOYEE    while i am able to store data in database i have 2 class one for String data and second fetching data Problem is coming in fetching data plz help

User · Answer

Hibernate has its own sql features that is known as hibernate query language. for retriving data from database using hibernate.

String sql_query = "from employee"//user table name which is in database.
Query query = session.createQuery(sql_query);
//for fetch we need iterator
Iterator it=query.iterator();
while(it.hasNext())
    {
         s=(employee) it.next();
System.out.println("Id :"+s.getId()+"FirstName"+s.getFirstName+"LastName"+s.getLastName);

   }

for fetch we need Iterator for that define and import package.

User · Answer

Query query   session createQuery  from Employee      Note  from Employee  here Employee is not your table name it s POJO name

User · Answer

I know that it is very late to answer the question  but it may help someone like me who spent lots off time to fetch data using hql  So the thing is you just have to write a query  Query query   session createQuery  from Employee      it will give you all the data list but to fetch data from this you have to write this line   List lt Employee gt  fetchedData   query list      As simple as it looks

User · Answer

try the class-name  Query query   session createQuery  from Employee      instead of the table name  Query query   session createQuery  from EMPLOYEE

User · Answer

Let me quote this   Hibernate created a new language named Hibernate Query Language  HQL   the syntax is quite similar to database SQL language  The main difference between is HQL uses class name instead of table name  and property names instead of column name   As far as I can see you are using the table name   So it should be like this   Query query   session createQuery  from Employee

User · Answer

The correct way from hibernate doc       Session s   HibernateUtil getSessionFactory   openSession        Transaction tx   null      try            tx   s beginTransaction                        here get object         List lt Employee gt  list   s createCriteria Employee class  list             tx commit           catch  HibernateException ex            if  tx    null                tx rollback                                  Logger getLogger  con   info  Exception      ex getMessage             ex printStackTrace System err         finally           s close             HibernateUtil code  can find at Google                public class HibernateUtil                    private static final SessionFactory tmrSessionFactory                  private static final Ejb3Configuration tmrEjb3Config                  private static final EntityManagerFactory tmrEntityManagerFactory                   static                        try                            tmrSessionFactory   new Configuration   configure  tmr cfg xml   buildSessionFactory                            tmrEjb3Config   new Ejb3Configuration   configure  tmr cfg xml                            tmrEntityManagerFactory   tmrEjb3Config buildEntityManagerFactory                           catch  HibernateException ex                            Logger getLogger  app   log Level WARN  ex getMessage                             throw new ExceptionInInitializerError ex                                                            public static SessionFactory getSessionFactory                         return tmrSessionFactory                                        getters and setters here

[java] how to fetch data from database in Hibernate

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