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第十四周实验
【例】功能要求：增加一新表XS_1，表结构和表XS相同，用来存放从XS表中删除的记录。
分析:
1、创建表 xs_1
SQL> create table xs_1 as select * from xs;
Table created
SQL> truncate table xs_1;
Table truncated题目：创建一个触发器，当XS表中记录被删除时，请备份下删除的记录，方式：写到新建表XS_1中,以备查看。
create or replace trigger del_xs
before delete on xs
for each row
begin
insert into xs_1(xh,xm,zym,xb,cssj,zxf)
values
(:old.xh,:old.xm, :old.zym, :old.xb, :old.cssj,:old.zxf);
end del_xs;
代码：
SQL> select *from xs_1;
XH XM ZYM XB CSSJ ZXF BZ
------ ------ ------ -- ----------- --- --------------------
SQL> select *from xs;
XH XM ZYM XB CSSJ ZXF BZ
------ ------ ------ -- ----------- --- --------------------
061101 王林 计算机 男 1986/2/10 50
101112 李明 计算机 男 1986/1/30 36
001 张琼 计算机 45 三好学生
121112 王小二 计算机 男 1986/1/30 36
SQL> delete from xs where xh=001;
1 row deleted
SQL> select *from xs_1;
XH XM ZYM XB CSSJ ZXF BZ
------ ------ ------ -- ----------- --- --------------------
001 张琼 计算机 45
SQL> select *from xs;
XH XM ZYM XB CSSJ ZXF BZ
------ ------ ------ -- ----------- --- --------------------
061101 王林 计算机 男 1986/2/10 50
101112 李明 计算机 男 1986/1/30 36
121112 王小二 计算机 男 1986/1/30 36
SQL>
综上所述：备份成功！
触发器示例2
功能需求：监控用户对XS表的操作，要求：当XS表执行插入、更新和删除3种操作后在sql_info表中给出相应提示和执行时间。
Create table sql_info(info varchar(10),time date);
思考：是否可以放到一个触发器中，如可以则需要判断
到底是哪种操作（插入还是更新还是删除）
create or replace trigger t2
after delete or insert or update on xs
for each row
declare
v_info sql_info.info%type;
begin
if inserting then
v_info:='插入';
elsif updating then
v_info:='更新';
else
v_info:='删除';
end if;
insert into SQL_INFo VALUES(v_info,sysdate);
end t2;
SQL> create table sql_info(info varchar(10),time date);
Table created
SQL> select * from sql_info;
INFO TIME
---------- -----------、
SQL> insert into xs(xh) values(21212);
1 row inserted
SQL> select * from sql_info;
INFO TIME
---------- -----------
插入 2023/12/8 1
SQL>
SQL> select * from xs;
XH XM ZYM XB CSSJ ZXF BZ
------ ------ ------ -- ----------- --- --------------------
061101 王林 计算机 男 1986/2/10 50
101112 李明 计算机 男 1986/1/30 36
121112 王小二 计算机 男 1986/1/30 36
21212
SQL> delete from xs where xh=21212;
1 row deleted
SQL> select * from xs_1;
XH XM ZYM XB CSSJ ZXF BZ
------ ------ ------ -- ----------- --- --------------------
001 张琼 计算机 45
21212
SQL> select * from sql_info;
INFO TIME
---------- -----------
插入 2023/12/8 1
删除 2023/12/8 1
SQL>
1.
SQL> create table emp_1 as select * from scott.emp;
Table created
SQL> truncate table emp_1;
Table truncated
SQL>
create or replace trigger del_scott
before delete on scott.emp
for each row
begin
insert into emp_1 (empno,ename,job,mgr,hiredate,sal,comm,deptno)
values (:old.empno,:old.ename,:old.job,:old.mgr,:old.hiredate,:old.sal,:old.comm,:old.deptno);
end del_emp;
测试;
SQL> delete from scott.emp where empno = 7499;
1 row deleted
SQL> select * from scott.emp;
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
----- ---------- --------- ----- ----------- --------- --------- ------
7369 SMITH CLERK 7902 1980/12/17 820.00 20
7521 WARD SALESMAN 7698 1981/2/22 1250.00 500.00 30
7566 JONES MANAGER 7839 1981/4/2 2975.00 20
7654 MARTIN SALESMAN 7698 1981/9/28 1250.00 1400.00 30
7698 BLAKE MANAGER 7839 1981/5/1 2850.00 30
7782 CLARK MANAGER 7839 1981/6/9 2450.00 10
7788 SCOTT ANALYST 7566 1987/4/19 3000.00 20
7839 KING PRESIDENT 1981/11/17 5000.00 10
7844 TURNER SALESMAN 7698 1981/9/8 1500.00 0.00 30
7876 ADAMS CLERK 7788 1987/5/23 1120.00 20
7900 JAMES CLERK 7698 1981/12/3 970.00 30
7902 FORD ANALYST 7566 1981/12/3 3000.00 20
7934 MILLER CLERK 7782 1982/1/23 1300.00 10
13 rows selected
SQL> select * from emp_1;
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
----- ---------- --------- ----- ----------- --------- --------- ------
7499 ALLEN SALESMAN 7698 1981/2/20 1600.00 300.00 30
SQL>
2.
create or replace trigger t2
after delete or insert or update on xs
for each row
declare
v_info sql_info.info%type;
begin
if inserting then
v_info:='插入';
elsif updating then
v_info:='更新';
else
v_info:='删除';
end if;
insert into SQL_INFo VALUES(v_info,sysdate);
end t2;
SQL> create table sql_info(info varchar(10),time date);
Table created
SQL> select * from sql_info;
INFO TIME
---------- -----------
SQL> insert into xs(xh) values(21212);
1 row inserted
SQL> select * from sql_info;
INFO TIME
---------- -----------
插入 2023/12/8 1
SQL> select * from xs;
XH XM ZYM XB CSSJ ZXF BZ
------ ------ ------ -- ----------- --- --------------------
061101 王林 计算机 男 1986/2/10 50
101112 李明 计算机 男 1986/1/30 36
121112 王小二 计算机 男 1986/1/30 36
21212
SQL> delete from xs where xh=21212;
1 row deleted
SQL> select * from xs_1;
XH XM ZYM XB CSSJ ZXF BZ
------ ------ ------ -- ----------- --- --------------------
001 张琼 计算机 45
21212
SQL> select * from sql_info;
INFO TIME
---------- -----------
插入 2023/12/8 1
删除 2023/12/8 1
SQL> update scott.emp set ename='CHenwang' where empno=7900;
1 row updated
SQL> select * from sql_info;
INFO TIME
---------- -----------
插入 2023/12/8 1
删除 2023/12/8 1
SQL>
3.
CREATE OR REPLACE TRIGGER op_emp
BEFORE INSERT OR UPDATE OR DELETE ON scott.emp
FOR EACH ROW
BEGIN
IF INSERTING THEN
DBMS_OUTPUT.PUT_LINE(:new.empno||' '||:new.ename);
ELSIF UPDATING THEN
DBMS_OUTPUT.PUT_LINE(:old.sal||' '||:new.sal);
ELSE
DBMS_OUTPUT.PUT_LINE(:old.empno||' '|| :old.ename);
END IF;
END op_emp;
SQL> set serveroutput on;
SQL> insert into scott.emp(empno) values(7369);
7369
1 row inserted
SQL> update scott.emp set ename='LAOLI' where empno=7369;
1 row updated
SQL> delete from scott.emp where empno = 7369;
7369 LAOLI
1 row deleted
4.
CREATE OR REPLACE TRIGGER t4
AFTER INSERT OR UPDATE OR DELETE
ON scott.emp
declare
v_1 number; v_2 scott.emp.sal%type;
begin
if inserting then
select count(*) into v_1 from scott.emp;
DBMS_OUTPUT.PUT_LINE('添加记录后总人数为'||v_1);
elsif updating then
select avg(sal) into v_2 from scott.emp;
DBMS_OUTPUT.PUT_LINE('更新记录后平均工资为'||' '||v_2);
else
for v_s in (select deptno,count(*) num from scott.emp group by deptno)
loop
DBMS_OUTPUT.PUT_LINE('删除记录后各个部门的部门号和人数为' ||v_s.deptno||' '||v_s.num);
end loop;
end if;
end t4;
SQL> insert into scott.emp(empno) values(7369);
7369
添加记录后总人数为13
1 row inserted
SQL> update scott.emp set ename='LAOLI' where empno=7369;
更新记录后平均工资为 2218.75
1 row updated
SQL> delete from scott.emp where empno = 7369;
7369 LAOLI
删除记录后各个部门的部门号和人数为30 5
删除记录后各个部门的部门号和人数为20 4
删除记录后各个部门的部门号和人数为10 3
1 row deleted