| END;
/
Q.编写一个数据库触发器以显示当任何时候雇员加薪时的加薪情况。
A.
CREATE OR REPLACE TRIGGER emp_SalUp
AFTER UPDATE OF sal ON emp
FOR EACH ROW
DECLARE
vsal NUMBER;
BEGIN
vsal:=NVL(:NEW.sal,0)-NVL(:OLD.sal,0);
IF vsal<=0 THEN
RAISE_APPLICATION_ERROR(-20001,''''Increased Salary is not zero and littler than zero'''');
END IF;
END;
/
Q.编写一个数据库触发器，它允许用户只在上午9.00到下午5.00之间执行DML任务。
A.
CREATE OR REPLACE TRIGGER operate_time_limited
BEFORE INSERT OR UPDATE OR DELETE ON emp
--FOR EACH ROW
DECLARE
vtime NUMBER;
BEGIN
vtime:=TO_NUMBER(TO_CHAR(SYSDATE,''''HH24''''));
IF vtime NOT BETWEEN 9 AND 17 THEN
RAISE_APPLICATION_ERROR(-20444,''''Sorry!Not Except 9AM and 5PM.'''');
END IF;
END;
/
Q.编写一个数据为触发器以检查某个组织中不能有两个总裁。
A.
CREATE OR REPLACE TRIGGER check_president
BEFORE INSERT OR UPDATE ON emp
FOR EACH ROW
WHEN (UPPER(NEW.job)=''''PRESIDENT'''')
DECLARE
vCount NUMBER;
BEGIN
SELECT COUNT(job) INTO vCount
FROM emp
WHERE UPPER(job)=''''PRESIDENT''''; --把总统的个数统计出来，当为0时，变量值为0
IF vCount>0 THEN
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