If you define more than one Select trigger on the same table, the column list
is optional, and the column lists for each trigger can be unique
or can duplicate that of another Select trigger.
A SELECT on the triggering table can activate the trigger in two
cases:
The SELECT statement references any column in the column list.
The SELECT event definition has no OF column list specification.
(Sections that follow, however, describe additional circumstances
that can affect whether or not a SELECT statement activates a Select
trigger.)
Whether it specifies one column or more than one column from the column list,
a triggering SELECT statement activates the Select trigger only once.
The action of a Select trigger cannot include an UPDATE, INSERT,
or DELETE on the triggering table. The action of a Select trigger
can include UPDATE, INSERT, and DELETE actions on tables other than
the triggering table. The following example defines a Select trigger
on one column of a table:
CREATETRIGGER mytrig
SELECTOF cola ON mytab REFERENCINGOLDAS pre
FOREACHROW (INSERTINTO newtab VALUES('for each action'));
You cannot specify a SELECT event for an INSTEAD OF trigger on
a view.