Marc Evans <Marc@SoftwareHackery.Com> writes:
> In the trigger, TG_ARGV[0] is the name of a column that I want to
> evaluate.
This is effectively impossible in plpgsql, because it's a statically
typed language --- it wants to know the type of every expression in
advance, and so such a thing couldn't work. Consider using one of the
other PLs instead.
regards, tom lane