Before statement-level trigger v16

This example shows a simple before statement-level trigger that displays a message before an insert operation on the emp table:

CREATE OR REPLACE TRIGGER emp_alert_trig
    BEFORE INSERT ON emp
BEGIN
    DBMS_OUTPUT.PUT_LINE('New employees are about to be added');
END;

The following INSERT is constructed so that several new rows are inserted upon a single execution of the command. For each row that has an employee id between 7900 and 7999, a new row is inserted with an employee id incremented by 1000. The following are the results of executing the command when three new rows are inserted:

INSERT INTO emp (empno, ename, deptno) SELECT empno + 1000, ename, 40
    FROM emp WHERE empno BETWEEN 7900 AND 7999;
New employees are about to be added

SELECT empno, ename, deptno FROM emp WHERE empno BETWEEN 8900 AND 8999;

     EMPNO ENAME          DEPTNO
---------- ---------- ----------
      8900 JAMES              40
      8902 FORD               40
      8934 MILLER             40

The message New employees are about to be added is displayed once by the firing of the trigger even though the result adds three rows.