常用数据库对象
常用的Oracle的数据库对象介绍：表、视图、序列、索引、同义词、约束、存储过程、存储函数、包和包体、触发器
视图 view
create or replace
view
empinfoview
as
select e.empno,e.ename,e.sal,e.sal*
12 annsal,d.dname
from emp e,dept d
where e.deptno=d.deptno;
with
read only;
ORA-
01031: 权限不足
grant
create view
to scott 授权创建视图
desc empinfoview
名称 是否为空? 类型
----------------------------------------- -------- ----------------------------
EMPNO
NOT
NULL
NUMBER(
4)
ENAME
VARCHAR2(
10)
SAL
NUMBER(
7,
2)
ANNSAL
NUMBER
DNAME
VARCHAR2(
14)
select *
from empinfoview;
EMPNO ENAME SAL ANNSAL DNAME
------ ---------- ---------- ---------- --------------
7369 SMITH
800
9600 RESEARCH
7499 ALLEN
1600
19200 SALES
7521 WARD
1250
15000 SALES
序列
sequence
create
sequence
myseq;
create
table
testseq (tid
number,tname
varchar2(
20));
select myseq.nextval
from dual; 序列的下个一值
NEXTVAL
----------
1
select myseq.currval
from dual; 序列的当前值
CURRVAL
----------
1
insert
into testseq
values(myseq.nextval,
'aaa');
insert
into testseq
values(myseq.nextval,
'aaa');
insert
into testseq
values(myseq.nextval,
'aaa');
insert
into testseq
values(myseq.nextval,
'aaa');
select *
from testseq;
TID TNAME
---------- --------------------
2 aaa
3 aaa
4 aaa
5 aaa
索引 index
SQL的执行计划
explain plan for
select *
from emp
where deptno=
10;
select *
from
table(dbms_xplan.display);
--------------------------------------------------------------------------
| Id | Operation |
Name |
Rows | Bytes | Cost (%CPU)|
Time |
--------------------------------------------------------------------------
|
0 |
SELECT
STATEMENT | |
3 |
261 |
3 (
0)|
00:
00:
01 |
|*
1 |
TABLE ACCESS FULL| EMP |
3 |
261 |
3 (
0)|
00:
00:
01 |
--------------------------------------------------------------------------
创建目录（索引）
create
index
myindex
on emp(deptno);
explain plan for
select *
from emp
where deptno=
10;
select *
from
table(dbms_xplan.display);
| Id | Operation |
Name |
Rows | Bytes | Cost (%CPU)|
Time |
--------------------------------------------------------------------------------
|
0 |
SELECT
STATEMENT | |
3 |
261 |
2 (
0)|
00:
00:
01 |
|
1 |
TABLE ACCESS
BY INDEX ROWID| EMP |
3 |
261 |
2 (
0)|
00:
00:
01 |
|*
2 | INDEX
RANGE SCAN | MYINDEX |
3 | |
1 (
0)|
00:
00:
01 |
同义词(别名)
synonym
show user
USER 为
"SCOTT"
select
count(*)
from hr.employees;
为hr.employees起别名
---> 同义词
create
synonym hremp for hr.employees;
select
count(*)
from hremp;
COUNT(*)
----------
107
约束
constraint
create
table
student(
sid
number
constraint student_pk
primary
key,
sname
varchar2(
20)
constraint student_name_notnull
not
null,
gender
varchar2(
2)
constraint student_gender
check (gender
in (
'男',
'女')),
email
varchar2(
40)
constraint student_email_unique unique
constraint student_email_notnull
not
null,
deptno
number
constraint student_fk
references dept(deptno)
on delete
set
null
);
check 检查
create
table
test3(
tid
number,
tname
varchar2(
20),
gender
varchar2(
2)
check (gender
in (
'男',
'女')),
sal
number
check (sal >
0)
);
存储过程 procedure
--打印Hello World
--创建存储过程
create
or
replace procedure sayhelloworld
as
--说明部分
begin
dbms_output.put_line(
'Hello World');
end;
--调用存储过程：
1、
exec sayhelloworld();
2、
begin
sayhelloworld();
sayhelloworld();
end;
/
--给指定的员工涨100，并且打印涨前和涨后的薪水
create
or
replace procedure raiseSalary(eno
in
number)
is
--定义变量保存涨前的薪水
psal emp.sal%
type;
begin
--得到涨前的薪水
select sal
into psal
from emp
where empno=eno;
--涨100
update emp
set sal=sal+
100
where empno=eno;
--这里不用commit 谁调用谁提交
dbms_output.put_line(
'涨前:'||psal||
' 涨后：'||(psal+
100));
end raiseSalary;
/
--查询某个员工的姓名 薪水和职位
/*
1、查询某个员工的所有信息 ---> out参数太多
2、查询某个部门中的所有员工信息 ----> 返回的是集合
*/
create
or
replace procedure queryEmpInformation(eno
in
number,
pename
out
varchar2,
psal
out
number,
pjob
out
varchar2)
is
begin
select ename,sal,job
into pename,psal,pjob
from emp
where empno=eno;
end queryEmpInformation;
存储函数
function
--查询某个员工的年收入
create or replace
function
queryEmpIncome(eno
in
number)
return
number
is
--定义变量保存月薪和奖金
psal emp.sal%
type;
pcomm emp.comm%
type;
begin
--得到月薪和奖金
select sal,comm
into psal,pcomm
from emp
where empno=eno;
--返回年收入
return psal*
12+nvl(pcomm,
0);
end queryEmpIncome;
包和包体 package
and package body
--2、查询某个部门中的所有员工信息 ----> 返回的是集合
create
or
replace package mypackage
is
type empcursor
is ref cursor;
procedure queryEmpList(dno
in
number,empList
out empcursor);
end mypackage;
create
or
replace package body mypackage
is
procedure queryEmpList(dno
in
number,empList
out empcursor)
as
begin
open empList for
select *
from emp
where deptno=dno;
end;
end mypackage;
触发器 trigger
每当成功插入新员工后，自动打印“成功插入新员工”
create
trigger
firsttrigger
after
insert
on emp
declare
begin
dbms_output.put_line(
'成功插入新员工');
end;
/
强制审计
标准审计（配置）
基于值的审计
细粒度审计
管理员审计
/*
实施复杂的安全性检查
禁止在非工作时间 插入新员工
1、周末: to_char(sysdate,'day') in ('星期六','星期日')
2、上班前 下班后：to_number(to_char(sysdate,'hh24')) not between 9 and 17
*/
create or replace
trigger
securityemp
before
insert
on emp
begin
if to_char(
sysdate,
'day')
in (
'星期六',
'星期日',
'星期五')
or
to_number(to_char(
sysdate,
'hh24'))
not between
9
and
17
then
--禁止insert
raise_application_error(-
20001,
'禁止在非工作时间插入新员工');
end
if;
end securityemp;
/
/*
数据的确认
涨后的薪水不能少于涨前的薪水
*/
create or replace
trigger
checksalary
before
update
on emp
for each
row
begin
--if 涨后的薪水 < 涨前的薪水 then
if :new.sal < :old.sal
then
raise_application_error(-
20002,
'涨后的薪水不能少于涨前的薪水。涨前:'||:old.sal||
' 涨后:'||:new.sal);
end
if;
end checksalary;
/