Lock table: How to notify others

Question

Hi,
I 've created a Stored Procedure that inserts into a table.
The first and last statement of by BEGIN...END part of the stored procedure locks the table successfully.
BEGIN
      LOCK TABLE MY_TABLE IN EXCLUSIVE MODE NOWAIT;
        COMMIT;
     LOCK TABLE MY_TABLE IN SHARE MODE NOWAIT;
EXCEPTION
     WHEN OTHERS THEN
           dbms_output.PUT_LINE(SQLERRM);
          ROLLBACK;
END;
/The purpose is to lock the table so that if another user accidentally tries to execute the script s/he won't be able to modify the data in the table.
However, if the procedure is already running when another user tries to execute it, the 2nd user simply sees the procedure to terminate very quickly (it normally takes around 15-20 minutes based on the data). No message that the table is locked or that the procedure is in progress from another user.
How can I notify the 2nd user that the procedure is already in progress from another user or that the table is locked? What should I put in the EXCEPTION part maybe to do that?
Thank you in advance.
Regards,
John.

Answer 1

PRAGMA EXCEPTION_INIT(already_lock, -54);is 54 value meant for in-buit exception table
le locked, if so, even without having a custom
exception, oracle by itself would have thrown it in
the second session, right???, please do correct me if
iam wrong,
-54, and yes it is.
>
what will be the impact if i have a WAIT instead of
f NOWAIT, will my second session just be on hold
waiting for lock to be released???Second session will wait... but WAIT doesn't exist, just write lock table t3 IN EXCLUSIVE MODE ;I advise you to read this for LOCK command : http://download-west.oracle.com/docs/cd/B10501_01/server.920/a96540/statements_914a.htm#2064408
and this for exceptions : http://download-west.oracle.com/docs/cd/B10501_01/appdev.920/a96624/07_errs.htm#784
Nicolas.