locking and web interfaces

Hi, I'm fairly new to this subject.

How does locking work when accessing the database via web interfaces?
Usually applications work in a browsing mode. When you click the edit 
button, the same data is presented in a form which can be submited for 
update.
Is that necessary? If we don't consider the security problems of being 
in 'edit mode' all the time, do we need to keep switching between modes?
And what I really want to know is that being web interfaces stateless, 
whatever builtin locking you implement it will drop as soon as the web 
server is done.
Would persistent connections fix this? Do people use this mode switching 
to implement their own locks?

Any pointers to literature on this?

Thanks.

PS: Should I send this to SQL? Whats the policy on cross-posting?

-- 
Dado Feigenblatt                                 Wild Brain, Inc.   
Technical Director                               (415) 216-2053
dado@wildbrain.com                               San Francisco, CA.