import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name = "player")
public class Player {
 @Id
 @GeneratedValue(strategy = GenerationType.IDENTITY)
 private Long IDnumber;
 
  @Column(length = 20)
 private String name = null;

  @Column(length = 52)
 private double roll = null;
 
@Lob
@Column(length=2147483647)
private byte[] picture;

@Column(length = 10)
private int strategy;

public Long getIDnumber( ) {
 return IDnumber;
}

public void setIDnumber( Long iDnumber ) {
 IDnumber = iDnumber;
}

public String getName( ) {
 return name;
}

public void setName( String name ) {
 this.name = name;
}

public double getRoll( ) {
 return roll;
}

public void setRoll( double roll ) {
 this.roll = roll;
}

public byte[] getPicture( ) {
 return picture;
}

public void setPicture( byte[] picture ) {
 this.picture = picture;
}

public int getStrategy( ) {
 return strategy;
}

public void setStrategy( int strategy ) {
 this.strategy = strategy;
}
 

}

<?xml version="1.0" encoding="UTF-8" ?>
<persistence xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd"
 version="2.0" xmlns="http://java.sun.com/xml/ns/persistence">
 <persistence-unit name="Contact DB" transaction-type="RESOURCE_LOCAL">
   <properties>
     <property name="javax.persistence.jdbc.driver" value="org.apache.derby.jdbc.EmbeddedDriver" />
     <property name="javax.persistence.jdbc.url"
       value=jdbc:derby://localhost:1527/contact;create=true" />
     <property name="javax.persistence.jdbc.user" value="nbuser" />
     <property name="javax.persistence.jdbc.password" value="yourPassword" />
     <property name="eclipselink.ddl-generation" value="create-tables" />
     <property name="eclipselink.ddl-generation.output-mode"
       value="database" />
   </properties>

 </persistence-unit>
</persistence>

@Override
   public int hashCode() {
       int hash = 0;
       hash += (idnr != null ? idnr.hashCode() : 0);
       return hash;
   }

   @Override
   public boolean equals(Object object) {
       // TODO: Warning - this method won't work in the case the id fields are not set
       if (!(object instanceof play)) {
           return false;
       }
     play other = (play) object;
       if ((this.idnr == null && other.idnr != null) || (this.idnr != null && !this.idnr.equals(other.idnr))) {
           return false;
       }
       return true;
   }

   @Override
   public String toString() {
       return "holdem.play[idnr=" + idnr + "]";
   }

EntityManagerFactory  factory = Persistence.createEntityManagerFactory("Contact DB");
   EntityManager em = factory.createEntityManager();

//begin a transaction
   em.getTransaction().begin();

//you can find that player like this....
Player player = em.find( entityClass, IDnumber);

//...or you can find the player like this
Query q = em.createQuery( "select e from "
       + Player.class.getSimpleName( ) + " e where e."
       + name+ "= :name" );

//set your query parameter for name
   q.setParameter( "name", "John Doe");
//Get the only player in the list
   q.setMaxResults( 1 );
Player player = (Player) q.getResultList( ).get( 0 );

//or get the whole list of players if you want
List<Player> players = q.getResultList( );


//then set whatever you want. It will update in the database automatically

player.setPoints(10);

   em.getTransaction().commit();
   em.close();