How to Lock Form

Question

Dear Members,
How to Lock a Form if two Users are working at the same time on that form.
I need to put a Lock if the form is used by another User and Release the Lock only when the User using it closes the form.
How can we achieve this in Oracle Forms 6i. we are on 11.5.10.2.
Thanks
Sandeep

Answer 1

Using Locking Mode will not stop the issue of one user being told that the record is locked by another. I'm not sure about For Update but one thing it certainly won't do is prevent 2 users inserting the same record, so one user could get an error to say the record already exists, when they commit. Anyway, what happens to the For Update lock when the form is committed?
[Dbms_Lock|http://www.psoug.org/reference/dbms_lock.html] can be used to solve the problem with the following process.
Create a new package variable, control block item or global to store a "lock handle" (varchar2(200)).
When a record is selected in the master block, attempt to release the lock for the stored "lock handle" using dbms_lock.release(lock_handle). Ignore the function's return value (except when developing/debugging!).
Now create a new lock handle using dbms_lock.allocate_unique(lock_name, lock_handle). The lock_name should be a function of the master record's primary key so that it is unique to the record. Store the lock handle in the new variable.
Reuest a lock for the new lock handle, using dbms_lock.request(lock_handle). If the function returns 0 then you have been granted the lock, otherwise you have not.
If you do not have the lock then you need to disable inserts, updates and deletes in the child block. It's nice to set the field backgrounds to grey as well. If you do have the lock then the block should be enabled and the field backgrounds returned to their original colour.
In post-form, release the lock whose handle is stored in the lock_handle variable.