oracle 主键 字典表,oracle 增 删 改 查 新建表 主键 序列 数据字典

------------数据字典------------

select * from dba_tab_cols a where a.table_name='DEMO'

create table demo

(

did number(6),

dname varchar2(10)

)

select * from lzb.emp

------------同义词---------

create or replace view view_demo as select did

编号1,dname 名称1 from demo

select * from view_demo

select * from tyc

------------序列-----------

create sequence seq_demo;

insert into demo values(seq_demo.nextval,'llll');

select * from demo

------------------------

--创建部门表

create table Dept(

dept_id int

primary key not null,

dept_name

varchar(30) not null

);

--创建用户表

create table tuser(

u_id int

primary key not null,--主键

u_username

varchar(20) unique not null,--唯一

u_password

varchar(20) not null,

u_sex

char(4) default '女' not null,--缺省

u_age int

check (u_age between 10 and 140),--约束

dept_id int

,

constraint

u_d_f foreign key (dept_id) references dept(dept_id)--外键

);

--添加约束

alter table tuser

add constraint u_sex check (u_sex='男' or u_sex='女');

--删除约束

alter table tuser

drop constraint u_sex;--check name

--修改字段

alter table tuser

modify u_sex char(4) default '男' not null;

-- SQL server 方式

alter table tuser

add constraint u_sex_d default '男' for u_sex with values;

Create or replace VIEW v_user

As

Select d.dept_name, u.u_username, u.u_password, u.u_sex

From dept d, tuser u

Where d.dept_id=u.dept_id;