Hi Jeff,
Marina is correct. Additional information about your problem:
Marina Vatkina wrote:
> Look at the orderapp in the JavaEE tutorial - it has orders and lineitems with
> overlapping PK/FK mapping. This is most probably what you need.
>
> regards,
> -marina
>
> jeff wrote On 03/14/07 11:25,:
>
>> in a one to many (or 1-1) relationship, i want the many's ID to
>> incorporate it's one's ID.
>>
>> for example, if a have a Computer that has Ports. each port has a type,
>> say "USB", "serial", etc. furthermore, say i can only have one of each
>> type of port in a particular Computer.
>>
>> many Computers can have a Ports of the same type. how do i represent
>> this? what is the ID for Port? the type is enough to ID it within the
>> Computer, but i don't know how to represent this in JP. i think i want
>> the Port's ID to incorporate the Computer's ID.
>>
Check out 2.1.4 "Primary Keys and Entity Identity" in the JPA spec. In
particular look for composite primary keys (see below).
>> in the database, i think this would mean that the table for Port has a
>> foreign key pointing back to the the ID column of the table for Computer.
>>
>>
You could model this situation using a composite primary key in the Port
object, and the relationship Computer <-> Port could be modeled in the
database like:
CREATE TABLE COMPUTER (
ID VARCHAR(32) PRIMARY KEY;
...
);
CREATE TABLE PORT (
ID VARCHAR(32);
COMPUTER_ID VARCHAR(32);
...
PRIMARY KEY(ID, COMPUTER_ID);
FOREIGN KEY (COMPUTER_ID) REFERENCES COMPUTER(ID);
);
HTH,
-- markus.
>> i hope this makes sense.
>> thanks!
>>
>>
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>>> to find your fit.
>>>