| From: | "Daniel Verite" <daniel(at)manitou-mail(dot)org> |
|---|---|
| To: | "Adrian Klaver" <aklaver(at)comcast(dot)net> |
| Cc: | pgsql-general(at)postgresql(dot)org,"Bob Pawley" <rjpawley(at)shaw(dot)ca> |
| Subject: | Re: Updating |
| Date: | 2008-03-17 11:54:21 |
| Message-ID: | 4e715e28-cdbe-4302-b644-5c14180ff5cb@mm |
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| Thread: | |
| Lists: | pgsql-general |
Adrian Klaver wrote:
> CREATE FUNCTION foo() RETURNS trigger AS
> $Body$
> BEGIN
> IF NEW.colname != OLD.colname THEN
> ..."Do something"..;
> RETURN whatever;
> ELSE
> RETURN NEW:
> END IF;
> END;
> $Body$ LANGUAGE plpgsql;
Beware that the "Do something" code path will not be taken when the
column goes from NULL to non-NULL or non-NULL to NULL.
In the general case where the column is nullable, better use "IS
DISTINCT FROM" instead of inequality:
IF NEW.colname IS DISTINCT FROM OLD.colname
Best regards,
--
Daniel
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