Hibernate keep old data - mysql

Question

I'm beginer in Hibernate and Spring MVC, and i have a repetitive problem on retrieving data, sometimes when i refresh my page or just submit a form, i get old data that i had updated or even deleted.
Here is my configurations file of hibernate :
<hibernate-configuration>
<session-factory>
<!-- Database connection settings -->
<property name="connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="connection.url">jdbc:mysql://localhost:3306/cotaDB18</property>
<property name="connection.username">root</property>
<property name="connection.password"></property>
<!-- JDBC connection pool (use the built-in) -->
<property name="connection.pool_size">1</property>
<!-- SQL dialect -->
<property name="dialect">org.hibernate.dialect.MySQLDialect</property>
<!-- Enable Hibernate's automatic session context management -->
<property name="current_session_context_class">thread</property>
<!-- Disable the second-level cache -->
<!-- <property name="cache.provider_class">org.hibernate.cache.NoCacheProvider</property> -->
<property name="hibernate.connection.isolation">4</property>
<!-- Echo all executed SQL to stdout -->
<property name="show_sql">true</property>
<!-- Drop and re-create the database schema on startup -->
<property name="hbm2ddl.auto">update</property>
</session-factory>
I retrieve data like this :
#SuppressWarnings("unchecked")
#Override
public List<Tache> getTachesByPhase(int idPhase) {
Session session = HibernateUtil.getSessionFactory().getCurrentSession();
session.beginTransaction();
String hql = "From Tache T where T.phase=" + idPhase + " Order by T.index";
Query query = session.createQuery(hql);
return query.list();
}
Please i need your help, i don't find the solution