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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