John Newby <[EMAIL PROTECTED]> wrote:
do you only need the column name when "UPDATE OF" is chosen and not the other 3?
Correct.
do you need either "BEFORE" or "AFTER" only when "INSERT", "DELETE", or "UPDATE" are chosen, but not when "UPDATE OF" is chosen?
BEFORE and AFTER keywords are optional. You may choose to use them, or omit them, equally with all four kinds of triggers.
when would the "WHEN" option be required
Never. It's always optional.
and what is the "expression" part of the WHEN clause?
An arbitrary expression, possibly using fields of the table the trigger is on. The trigger only fires when the expression evaluates to true.
Igor Tandetnik
