Returning primary from creation - using triggers

Question

Evening,
I currently have an entity bean that has its' primary key value defined by a Trigger on my Oracle database.
So I have a situation where the key is always initialy set to Zero however, the trigger re-assigns the key on the databases INSERT method.
So my question is two fold then. Firstly does the entity bean assume that its' key value is still Zero or should the get method return the new key?
Secondly, how can I pass the new key value back to the entity beans container(each entity is wrapped in a session bean). At present I recieve an error when attempting to return the key value imediately after creating the entity bean so I presume I am going about the problem the wrong way.
Any ideas?
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Answer 1

Not to butt in, but why are you guys not using an identity column in
the db? That seems to be the logical solution if you have a truely
unique, db assigned pk.Unfortunately Oracle does not have identity columns. You can simulate an identity column to some extend by using a sequence and an insert trigger for each table.
Example (note I am not an Oracle guru):
CREATE SEQUENCE SQ_Logs MINVALUE 1 MAXVALUE 2147483647 NOCYCLE NOCACHE;
CREATE TABLE Logs
LogId NUMBER(10) NOT NULL,
LogDateTime DATE NOT NULL,
Severity CHAR(1) NOT NULL,
Message VARCHAR2(250) NOT NULL,
CONSTRAINT PK_Logs PRIMARY KEY (LogId),
CONSTRAINT UK_Logs UNIQUE (LogDateTime, Severity, Message)
CREATE TRIGGER TR_Insert_Logs BEFORE INSERT ON Logs
FOR EACH ROW
BEGIN
SELECT SQ_Logs.NEXTVAL INTO :NEW.LogId FROM DUAL;
END;
In the BMP-bean ejbCreate() method you insert the LogDateTime, Severity and Message values. The primary keyis set by the trigger. Then you lookup the primary key by using based on the alternate key (LogDateTime, Severity, Message).
The advantage of this solution is that your EJBs are database independent. The bad news is that each table requires an alternative unique key to locate the auto-generated primary key.
I have never implemented this for CMP-beans (I have read somewhere that EJB 2.1 solves this issue).
Ronald Maas