Oracle表的创建与管理

--表的创建与管理

--表的创建

create table member(

mid number(5),

name varchar2(50) default '无名氏',

age number(3),

birthday date default sysdate,

note clob

);

select * from tab;

desc member;

insert into member(mid,name,age,birthday,note)

values (1,'陈飞鹏',30,to_date('1992-09-12','yyyy-mm-dd'),'总公司活动提倡者');

insert into member(mid,name,age,birthday,note)

values (2,'董鸣楠',29,to_date('1980-08-13','yyyy-mm-dd'),'积极响应者');

select * from member;

--表的复制

drop table myemp;

create table myemp as select * from emp;

select * from myemp;

create table myemp10

as

select * from emp where deptno=10;

select * from myemp10;

create table employee1

as

select * from emp where 1=2;

select * from employee1;

desc employee1;

create table department1

as

select d.deptno,d.dname,d.loc,

count(e.empno) count,sum(e.sal+nvl(e.comm,0)) sum,

round(avg(e.sal+nvl(e.comm,0)),2) avg,max(e.sal) max,min(e.sal) min

from emp e,dept d

where e.deptno(+)=d.deptno

group by d.deptno,d.dname,d.loc

order by d.deptno;

--数据表的重命名

select * from department1;

select * from user_tables;

rename member to mldnuser;

select * from user_tables;

--截断表 desc

truncate table mldnuser;

select * from mldnuser;

rollback;

drop table mldnuser;

drop table myemp;

drop table myemp10;

drop table employee1;

drop table department1;

select * from tab;

flashback table myemp to before drop;

select object_name,original_name,operation,type from recyclebin;

select * from myemp10;

drop table myemp purge;

drop table myemp10 purge;

purge table myemp;

purge recyclebin;

--修改表结构

drop table member purge;

create table member(

mid number,

name varchar2(50) default'无名氏'

);

insert into member(mid,name)values(1,'李兴华');

insert into member(mid,name)values(2,'董鸣楠');

insert into member(mid,name)values(3,'王月清');

commit;

select * from member;

alter table member add(age number(3));

alter table member add(sex varchar(10) default'男');

alter table member add(photo varchar2(100) default'nophoto.jpg');

desc member;

alter table member modify(name varchar(30));

alter table member modify(sex varchar2(3) default'女');

alter table member drop column photo;

alter table member drop column age;

alter table member set unused(sex);

alter table member set unused column name;

select * from member;

alter table member drop unused columns;

--添加注释

drop table member purge;

create table member(

mid number,

name varchar2(50) default'无名氏',

age number(3),

birthday date

);

commit;

select * from user_tab_comments where table_name='MEMBER';

comment on table member is '用于记录参加活动的成员信息';

select * from user_col_comments where table_name='MEMBER';

comment on column member.mid is '参加活动的成员编号';