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Hibernate version: 3.1

Name and version of the database you are using: SQL Server

Hello,
We have the following tables in our database.

Table 1
Part_Id - int identity (10) - Primary key
Part_Code - Char (10)
Part_Name - Varchar (50)
Deleted - int(1) - value zero or one


Table 2
Part_Id - int(10) - Foreign key -->Table1.Part_Id
Replacing_Part_Id - int(10) - Foreign key-->Table1.Part_Id
Deleted - int(1) - value zero or one
Part_Id & Replacing_Part_Id is a composite primary key in table2.


Requirements: Rows should not be deleted physically in the database. They should be marked as deleted. Value 0 in Deleted column indicates row is not deleted. Py key value in Deleted column indicates row is deleted.

Please let me know how to create hbm mappings and java class for above schema?

Considering your requirement on the deleted item, also considering you have a property to manage in your many to many mapping table, you should do with 2 associations (*...1 and 1..*)

class for table 1 which has a one to many association on table2 (part_id -> part_id)
class for table 2 which has a many to one association on table 1(replacing_part_id -> part_id)

The composite key is documented in hibernate docs, as are the 'one to many' and the 'many to one' associations.

Also, don't activate the 'on delete cascade' in you hbm :) (Well according to your requirements, you never delete anyway)

Many thanks tchize!!

Sorry to be so naive. I am very new to hibernate. What is the basic difference between 'one to many' and 'many to one' association in hibernate? Can I map my classes like i have defined below?

Class for table 1
has a one to many association on table2 (part_id -> part_id)
has a one to many association on table 2(part_id -> replacing_part_id)

a) inverse atttibute is set to "true" for both these mappings.
b) Class has two HashSet instance variables.

class for table 2
has Part as the instance variable.

Is this correct? Please let me know.

the type of association rules how hibernate will manage update / insert in database.

one to many and many to one is just a matter of the side you look the association from. (at SQL level there is no difference as SQL queries allows you to explore association both ways). However at objects level, you can only explore an association in a given direction only if there are appropriate getters. If you want to explore a given association both way, you have to put appropriate getters on both classes. Hibernate requires you to create a descriptor for each class. This mean you have to describe the association, in the good direction, for each descriptor. But you seem to have already understood it considering your suggested code.


i'll say, table 2 has two parts and not one (one part representing the part_id field and another part representing the replacing_part_id field :)
i suppose you plan to have the one to many association represented by a <set ...> tag in .hbm overall it seems to correspond to you request :)

Many thanks tchize!! One last question!!! What is the need/advantage of having two parts instance variable in class2?

I have defined my mappings for class2 & class 1 as

CLASS2




CLASS1





Please let me know!

It just comes from your sql definition. table2 has 2 foreign keys, (PART_ID and REPLACING_PART_ID), so obviously you need two properties in CLASS2 to reprensent this (one which correspond to REPLACING_PART_ID and one which correspond to PART_ID)