How can I restrict more then one user to access the table?

Question

Hi !
I have a problem and two solutions and I am a bit confused as to
which one is the best one and/or can there be any better way of
handling the problem ?
Problem : I have to update a key field of a table when I update
it in the form 5.0 screen. I am basically doing a maintenance of
a table and if a certain field is updated then the change has to
be reflected in two more tables. But the issue is that the field
is a part of the key in those two tables. So all I can think of
is that I need to insert new set or rows for that new value of
the field and delete the old set of records for old values of
the field.
There are two ways of doing it;
1.One option can be to explicitely define two cursors separately
and fetch the values in them one by one and then insert the new
records and then delete the old records in both the tables. This
I feel will be a cumbersome process both in terms of processing
time and the coding.
2.Second option I was thinking can be to create two flat tables
(without keys) and insert the values in them and update the
changed field there and then insert the rows in the respective
tables. Delete the old records in the main tables and delets the
records in these flat tables. This is a bit more faster and
easier to predict and code. This seems to be a better option for
me.
Any comments on these ?
In both the cases I was thinking of making some provision so
that more then one person can't update the table simultaneously.
Since if there are more then one persons doing the processing
then some inconsistency might creep into the whole process.
This is easier to do in the second process as if I check the
data in the flat tables and if there is some data then I can
presume that some one is doing the processing and I can ask the
other person to hold for a while. But in this case how can I
stop more then two people to simultaneously check for the empty
table and start inserting the record ?
I was just thinking of having a sepatare table having only one
field and this will be a key field and as the process begins the
process will insert a fix value say 'Y' in the key field and at
the end of the process the record will be deleted and this way
we can restrict the user to access the process more then one at
a time..? Since you can't have same value of the key in a table
more then once.
Any better way of handling it will be deeply appreciated.
How about locking the table at the begining and releasing the
lock at the end ? Will there be any issue in that? since I am
inserting and deleting the rows in the same transaction.
Comments welcome,
Shobhit
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Answer 1

How about performing the update IN the database using a stored
procedure?
By using non-database fields on your form to get the
information, you can then call the procedure in the database to
perform the updates. If an error occurs in the procedure you
rollback, if necessary, and send a message or status back to the
form. If it succeeds you might wish to commit and then re-
execute the form's query -- using either the original key values
or the new key values...
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