hibernate java mysql orm sql

Hibernate error on update : could not execute statement, the right syntax to use near ‘index=1’

I’m developing a desktop application using netbeans with Hibernate and MySQL . When I add a new record to the database it’s totally working but when I try to update an object field I have this error :

could not execute statement
INFO: HHH000010: On release of batch it still contained JDBC statements
Jan 17, 2015 2:47:00 PM org.hibernate.engine.jdbc.spi.SqlExceptionHelper$StandardWarningHandler logWarning
WARN: SQL Warning Code: 1064, SQLState: 42000
Jan 17, 2015 2:47:00 PM org.hibernate.engine.jdbc.spi.SqlExceptionHelper$StandardWarningHandler logWarning
WARN: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'index=1' at line 1

Java code :

private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {                                         
Session session = null;
try {
session = HibernateUtil.getSessionFactory().openSession();
Student student = (Student) session.get(Student.class, new Integer(1));
System.out.println(student.getIndex()+" "+student.getName()+" "+student.getMark());
} catch (Exception e) {

hibernate.cfg.xml :

<property name="hibernate.dialect">org.hibernate.dialect.MySQLInnoDBDialect</property>
<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="hibernate.connection.url">jdbc:mysql://localhost:3306/studentsdb?zeroDateTimeBehavior=convertToNull</property>
<property name="hibernate.connection.username">root</property>
<property name="">update</property>
<mapping resource="entity/Student.hbm.xml"/>

Hibernate mapping xml :

<class name="entity.Student" table="student" catalog="studentsdb">
<id name="index" type="java.lang.Integer">
<column name="index" />
<generator class="identity" />
<property name="name" type="string">
<column name="name" length="20" not-null="true" />
<property name="surname" type="string">
<column name="surname" length="20" not-null="true" />
<property name="mark" type="double">
<column name="mark" precision="22" scale="0" not-null="true" />