hibernate w/derby simple crud

hi-

i am really new to hibernate.
i thought it would be cool to use in my hobby.
i want to make the code that deals with the db more readable in my projects.
i hope hibernate can help me in that regard.

i am trying to add a record?
i get an error that says attempting to modify an identity column.
i didnt specify the identity column in my constructor call.

i saw how to iterate through the table (read using HQL) but am looking
for an example of create,update, delete. i am missing the example
somewhere in my book (hibernate in action).

with delete i probably just set part of a collection to null....right?

if i can get help on this identity column issue, i may be able to figure the
examples out myself.
thank you,
jim

Session session = HibernateUtil.getSessionFactory().openSession();
Transaction tx = session.beginTransaction();
Date d1 = new Date(2006-10-14);
Date d2 = new Date(2006-10-15);
Accounts accounts = new Accounts("boo",d1,d2);

session.save(accounts);
tx.commit();
session.close();

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// pojo
package bcalcpkg;
// Generated Jan 6, 2007 1:38:27 AM by Hibernate Tools 3.2.0.beta8
import java.util.Date;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;
import javax.persistence.GeneratedValue;
/**
 * Accounts generated by hbm2java
 */
@Entity
@org.hibernate.annotations.Entity(
  dynamicInsert = true, dynamicUpdate = true)
@Table(name = "ACCOUNTS", schema = "USER1", uniqueConstraints = {})
public class Accounts implements java.io.Serializable {
 // Fields
 @Id @GeneratedValue
 @Column(name = "ACCOUNTID")
 private int accountid;
 @Column(name = "ACCOUNTNAME")
 private String accountname;
 @Column(name = "ACCOUNTOPEN")
 private Date accountopen;
 @Column(name = "ACCOUNTCLOSE")
 private Date accountclose;

 // Constructors
 /** default constructor */
 public Accounts() {
 }
 /** minimal constructor */
 public Accounts(int accountid, String accountname, Date accountopen) {
  this.accountid = accountid;
  this.accountname = accountname;
  this.accountopen = accountopen;
 }
 /** full constructor */
 public Accounts( String accountname, Date accountopen,
   Date accountclose) {
  //this.accountid = accountid;
  this.accountname = accountname;
  this.accountopen = accountopen;
  this.accountclose = accountclose;
 }
 //public Accounts(String text) {
  //this.text = text;
  //}

 // Property accessors
 @Id
 @Column(name = "ACCOUNTID", unique = true, nullable = false, insertable =
true, updatable = true)
 public int getAccountid() {
  return this.accountid;
 }
 public void setAccountid(int accountid) {
  this.accountid = accountid;
 }
 @Column(name = "ACCOUNTNAME", unique = false, nullable = true, insertable =
true, updatable = true, length = 50)
 public String getAccountname() {
  return this.accountname;
 }
 public void setAccountname(String accountname) {
  this.accountname = accountname;
 }
 @Temporal(TemporalType.DATE)
 @Column(name = "ACCOUNTOPEN", unique = false, nullable = true, insertable =
true, updatable = true, length = 10)
 public Date getAccountopen() {
  return this.accountopen;
 }
 public void setAccountopen(Date accountopen) {
  this.accountopen = accountopen;
 }
 @Temporal(TemporalType.DATE)
 @Column(name = "ACCOUNTCLOSE", unique = false, nullable = true, insertable
= true, updatable = true, length = 10)
 public Date getAccountclose() {
  return this.accountclose;
 }
 public void setAccountclose(Date accountclose) {
  this.accountclose = accountclose;
 }

}