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;
/
转载自：https://blog.csdn.net/weixin_38008316/article/details/80543453