?Oracle Transactions: BeginTrans...Select for update...Update...Commit


I am using SQL-links with Oracle 7 and I want
to add some transaction control like this:

if Database1.StartTransaction then
   if 'Select * from table1 FOR UPDATE' then
        if 'update table1 set col1='X'' then
        msg('Cannot lock table1 for update');
        msg('Cannot start transaction');

I can basically get these commands to work, but
does anyone know what happens if there is a previous lock
on the table?

I'd like an immediate response if the
        'select * from table1 FOR UPDATE'
command doesn't succeed, not a seemingly endless wait
for the lock to be released. Is there a parameter to
set for connection time out??

(In my actual case, I am trying to lock a single row for
update, not the whole table as shown in this rough example.)

All comments and suggestions are appreciated