users@glassfish.java.net

RE: entity relation

From: Eve Pokua <gorgeous65_at_msn.com>
Date: Fri, 20 Mar 2009 16:43:18 +0000

Hi,

 

 

thanks,

 

Please, how do I install Eclipselink driver?

I've downloaded and followed the instructions but not working.

 

thanks

 

eve


 


From: andrei.ilitchev_at_oracle.com
To: persistence_at_glassfish.dev.java.net
Date: Fri, 20 Mar 2009 10:15:56 -0400
Subject: Re: entity relation




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
 
 



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