userInfo (
,monospace; direction: ltr; border-top-style: none; color: black; font-size: 10pt; border-left-style: none; overflow: visible; padding-top: 0px">       address varchar2(50),monospace; direction: ltr; border-top-style: none; color: black; font-size: 10pt; border-left-style: none; overflow: visible; padding-top: 0px">       email varchar2(25),monospace; direction: ltr; border-top-style: none; color: black; font-size: 10pt; border-left-style: none; overflow: visible; padding-top: 0px">       tel number(11)
名称的：
  userInfo (
 ,--主键
 ,--非空
 18,monospace; direction: ltr; border-top-style: none; color: black; font-size: 10pt; border-left-style: none; overflow: visible; padding-top: 0px">       email varchar2(25) ,--唯一
 dept(deptno)—外键
名称：
 id_pk  ,monospace; direction: ltr; border-top-style: none; color: black; font-size: 10pt; border-left-style: none; overflow: visible; padding-top: 0px">           name varchar2(20)  name_nn  ,monospace; direction: ltr; border-top-style: none; color: black; font-size: 10pt; border-left-style: none; overflow: visible; padding-top: 0px">           sex number(1),monospace; direction: ltr; border-top-style: none; color: black; font-size: 10pt; border-left-style: none; overflow: visible; padding-top: 0px">           age number(3)  18,monospace; direction: ltr; border-top-style: none; color: black; font-size: 10pt; border-left-style: none; overflow: visible; padding-top: 0px">           birthday ,monospace; direction: ltr; border-top-style: none; color: black; font-size: 10pt; border-left-style: none; overflow: visible; padding-top: 0px">           address varchar2(50),monospace; direction: ltr; border-top-style: none; color: black; font-size: 10pt; border-left-style: none; overflow: visible; padding-top: 0px">           email varchar2(25)  email_uqe ,monospace; direction: ltr; border-top-style: none; color: black; font-size: 10pt; border-left-style: none; overflow: visible; padding-top: 0px">           tel number(11),monospace; direction: ltr; border-top-style: none; color: black; font-size: 10pt; border-left-style: none; overflow: visible; padding-top: 0px">           deptno number(2)  dept_deptno_ref  dept(deptno)
 id_pk   (id),--也可以两个以上，联合主键
 dept_deptno_ref   (deptno)  dept(deptno),monospace; direction: ltr; border-top-style: none; color: black; font-size: 10pt; border-left-style: none; overflow: visible; padding-top: 0px">            emial_name_uqe  (email,name)
  userInfo (msn varchar2(20));
  userInfo (msn varchar2(25));
  userInfo (msn);
  userInfo   id_pk;
  userInfo   id_pk   (id);
  v$_dept_view

 deptno,dname  dept;
  v$_dept_view compile;
提示：视图一般是一个表或多个表的查询或子查询，这样可以减少代码量，但同时增加了对数据库视图的维护程度，如：某个表字段被删除或是修改，视图也要重新创建或修改，同时占用了数据库的一部分空间；视图就是一个虚拟的表格；
  idx_dpt_dname  dept(dname);
  idx_dept_dname_deptno  dept(dname,deptno);
   idx_emp_ename  scott.emp(ename);
  idx_emp_rev_no  scott.emp(empno) reverse;
 bitmap  idx_emp_name  scott.emp(dname);
  tab (
  ,monospace; direction: ltr; border-top-style: none; color: black; font-size: 10pt; border-left-style: none; overflow: visible; padding-top: 0px">        name varchar2(20)
;
  idx_name  (col) /;
提示：当给表创建主键或唯一键约束时，系统也会创建一个约束给该字段；同样创建索引也会占用数据库空间；索引在访问、查询的时候效率有提高，但是在修改表的时候效率就会降低；
  seq;
 seq.nextval  dual;
 tab (sql.nextval,‘music’);
  seqtab
  2 –从2开始
 3—每次加3
修改序列 ，不能修改起始值
  seqtab
 synonym scott_emp  scott.emp;
  synonym scott_dept  scott.dept;
 *  scott_emp;
 *  scott_dept;
 tablespace HooMS

 5M
  2M maxsize 10M;
用户、分配可以操作表空间
  hoo
 hoo
 tablespace  HooMS
 tablespace temp;
 tablespace myMS

 1M
;
修改表空间大小
 
添加数据文件
 tablespace myMS
 datafile 
 1M;
文件自动增长
  

  2M maxsize 4M;
重命名
 hooMS;
 tablespace hooMS
;
;
 tablespace hooMS online;
删除无数据的表空间
 tablespace hooMS;
删除带数据的表空间
 tablespace hooMS