Can 3 class map on 1 table?

asklxf · **Joined:** Fri Feb 17, 2006 12:18 am **Posts:** 11

Hi, I have 3 class with one-one-one relationship to map. so I want to map these 3 class on 1 same table:

Code:

class A { 
Long ID; 
String a; 
} 

class B { 
Long ID; 
String b; 
} 

class C { 
Long ID; 
String c; 
} 

can these 3 class map on 1 table:

Code:

ID BIGINT 
VARCHAR(10) A 
VARCHAR(10) B 
VARCHAR(10) C 

and use 1 same primary key?

thx!

steckemetz · **Posted:** Fri Feb 17, 2006 4:02 am

Perhaps you can use component mapping ?
See chapter 5.1.13.

asklxf · **Joined:** Fri Feb 17, 2006 12:18 am **Posts:** 11

steckemetz wrote:

Perhaps you can use component mapping ?
See chapter 5.1.13.

I know component cannot have OID, but there is 3 individual businesses based on 1 table.

for example, a "Customer" table with many fields.

the login system only needs fields: ID, username, password.

the shoping system only needs fields: ID, truename, address, zipcode.

the email system only needs fields: ID, email.

maybe there will be new business needs other fields. e.g.: a blog system needs ID, blogTitle, articleCount, imageCount ...

these 3 class are not related but share the same primary key. also i don't want to use 1 class to hold all fields that may reduce performance.

can I use 3 classes but map them onto 1 table?

the-gtm · **Joined:** Wed Feb 08, 2006 3:59 pm **Posts:** 75

As far as I know it is possible to map as many classes on a single table as you want. However I wouldn't recommend it as it would defeat most Hibernate features : if you save one 'A', how is Hibernate supposed to know that a 'B' and a 'C' have been created to ?
In your case, I would use a single class, implementing 3 interfaces IA, IB, IC, and maybe a factory for instanciations.
If your concern is performance (don't want to load Bs properties if you just need an A), you can still use property lazy fetching.
http://www.hibernate.org/hib_docs/v3/reference/en/html/performance.html#performance-fetching-lazyproperties

Hope this helps