Re: autoupdating mtime column

David Garamond wrote:
> On 8/4/06, Richard Huxton <dev@archonet.com> wrote:
>> David Garamond wrote:
>> > Dear all,
>> >
>> > Please see SQL below. I'm already satisfied with everything except I
>> > wish in
>> > #4, mtime got automatically updated to NOW() if not explicitly SET in
>> > UPDATE
>> > statement. Is there a way to make the mtime column behave more like I
>> > wanted? Thanks in advance.
>>
>> Just check for OLD.mtime = NEW.mtime, or am I missing something here?
> 
> How do I differentiate between:
> 
> UPDATE t SET mtime=mtime ...;
> 
> in which mtime is specifically set and should not change, and
> 
> UPDATE t SET foo=bar ...;
> 
> in which mtime is not mentioned and should be updated automagically to
> NOW().

You can't. The trigger knows nothing about the original statement, just 
the old and new tuple values.

You could use SET foo=DEFAULT, but that's neither more or less 
convenient than now() in my eyes.

--   Richard Huxton  Archonet Ltd