Re: saving object using sequence as ID, help!

On Fri, 05 Apr 2002, hxzhang_at_binary-solutions.net wrote:
>
> I have a table with each row corresponds to a javabean object. The
> objects don't necessarily have a primary key, so i use a sequence
> number as its primary key, and a trigger to assign the sequence number
> to its ID column when a new object is inserted into the database.
>
> However, after I insert the object into the table, how can i know the
> object's ID in the table? If I simply do a "..._seq.cur_val", it is
> not safe when multiple users can access the database and save their
> javabean into it at the same time.

curr_val is unique per session. Try it out.

SQLPLUS1> select ..._seq.next_val from dual;
SQLPLUS2> select ..._seq.next_val from dual;
SQLPLUS1> select ..._seq.curr_val from dual;
SQLPLUS2> select ..._seq.curr_val from dual;

Do you see that both sessions are quaranteed a unique sequence number? Try it with three, or four or five sqlplus sessions. Oracle guarantees a unique sequence number.

-- 
Galen deForest Boyer
Sweet dreams and flying machines in pieces on the ground.