In Eclipselink
@GeneratedValue(strategy = GenerationType.AUTO)
is equivalent to:
@GeneratedValue(generator="SEQ_GEN")
where "SEQ_GEN" generator by default is:
@TableGenerator(name="SEQ_GEN", table="SEQUENCE", pkColumnName="SEQ_NAME", valueColumnName="SEQ_COUNT", pkColumnValue="SEQ_GEN")
That works on all database platforms.
Note that the user can re-define AUTO by specifying their customary SEQ_GEN generator, for instance:
@SequenceGenerator(name="SEQ_GEN", sequenceName="MY_SEQ", allocationSize=10)
----- Original Message -----
From: Axl Mattheus
To: persistence_at_glassfish.dev.java.net
Sent: Friday, March 20, 2009 12:22 AM
Subject: Re: entity relation
On the id generation:
What database are you using? The 'AUTO' generation strategy should actually be called 'DIFFERENT_FOR_DIFFERENT_DATABASES' or 'SOMETIMES_DOESNT_WORK' would also be a good name...
ax/
2009/3/20 Eve Pokua <gorgeous65_at_msn.com>
Hi,
everyone,
please read the following and let me know if I am on the right track.
I've entities-
Iteams
Customer
Order
Orderline
The Orderline breaks down the many-to many relationship for order and Iteams.
Now, I do remember creating the tables before I normalised them, the system would
create an extra table(which I did not specified) for Iteams and Order. So it would
insert the id (s) of Iteams and Order everytime it was created.
The Orderline has fields -
orderid
itemid
cusid
qauntity.
If i move the fields back into Order and create the many-to-many relationship
between Order and Iteams, then the system will many it for me. Is this the
best way to manage an application like this or should I stick to my normalisation
as mentioned above.
Also, I would like the DB to generate the id fields automatically, so in my entities,
I've specified as-
@Entity
@Table(name="ORDERS")
public class Orderent implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long ordID;
.....
But the DB keeps asking for id when i enter new dada. Now, how do I manage a situation
like this?
I'd appreciate any suggestions. Thanks
eve
----------------------------------------------------------------------------
Windows Live Hotmail just got better. Find out more!