Обсуждение: protecting a field after creation

Hello,

Is there a way (outside of RULEs and  TRIGGERs) to make a field
read-only once it is INSERTed or assigned its default value? I'm
thinking, for example, of the "created" column that I add to most
tables, holding the row's creation timestamp.

Thanks in advance,

-- 
Louis-David Mitterrand - ldm@apartia.org - http://www.apartia.org

Murphy's Guide to Science:  If it's green or squirms, it's biology.  If it stinks, it's chemistry.  If it doesn't work,
it'sphysics.
 

Louis-David Mitterrand <cunctator@apartia.ch> writes:
> Is there a way (outside of RULEs and  TRIGGERs) to make a field
> read-only once it is INSERTed or assigned its default value? I'm
> thinking, for example, of the "created" column that I add to most
> tables, holding the row's creation timestamp.

An on-update trigger seems like a very simple solution here.
You could either copy the old value into the new, or raise an
error if they are different, depending on what you want.
        regards, tom lane