[jboss-user] [Persistence, JBoss/CMP, Hibernate, Database] - Re: How to use @Id @GeneratedValue(strategy=GenerationType.A

[rabbiaqaswar]

When you will create your entity you will only have to set the desc property. The 'id' property will be set since it has these @Id @GeneratedValue(strategy=GenerationType.AUTO) annotations.

The database end depends upon the table generation strategy in your persistence.xml file. If this is what you have in persistence.xml:
 
  | <properties>
  |       <property name="hibernate.hbm2ddl.auto" value="create"/>
  | </properties>
  | 
OR 
  | <properties>
  |       <property name="hibernate.hbm2ddl.auto" value="update"/>
  | </properties>

Then you dont have to create the tables yourself, they'll be created. If you want to create the tables yourself then just like anyother column in a table you should also create the column for your id. 

The @GeneratedValue annotations generates only int, Long or String values(but do check for yourself). So you should check what should be the datatype of your id. Say i have a table Customer in db with property Number CUSTOMERID. In my entity Customer, i will have property Long customerId. Then i use:


  | @Id 
  | @GeneratedValue(strategy=GenerationType.AUTO) 

It works fine.

hope this helps!

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