Regarding problems when adding foreign keys

Can't find the original post in c.d.i. but I have seen some answers on other forums that copy from c.d.i. My original post was: Problem 1. If it is not possible to lock table A in exclusive mode I can't add the foreign key. Why is there a need for an exclusive lock on table A in this situation ? >> I did receive good reasons for this, the question is answered, thank you ! Problem 2. If I succed to add the foreign key I get -710 errors when trying to update table A.Why the -710 error on table A ? The solution I have found is to do an update statistics on table A. Is there other ways around the problem ? >> I should have been more clear on this. I am aware of the problem with prepared statements, but we get the -710 problem not only for prepared statements but also for a normal delete or update against table A issued from dbaccess. Table A has a trigger that calls a SPL, can this lead to this problem ? Ulf