Stand-alone SELECT statements

Suppose you define the following Select trigger on a table:
CREATE TRIGGER hits_trig SELECT OF col_a ON tab_a
   REFERENCING OLD AS hit
   FOR EACH ROW (INSERT INTO hits_log
                 VALUES (hit.col_a, CURRENT, USER));
A Select trigger executes when the triggering column appears in the select list of a stand-alone SELECT statement. The following statement executes a triggered action on the hits_trig trigger for each instance of a row that the database server returns:
SELECT col_a FROM tab_a;