SQL-- user, tablespace, table, ORACLE

one:

sys superuser

system

scott/tiger

===============================================

in cmd

1. Log in with sys;

       sqlplus sys/1234@myoracle as sysdba

 --Query the current instance name

      select instance_name from v$instance;

--Query the current database name

      select name from v$database;

2. If the scott/tiger user is locked;

alter user scott account unlock;//Unlock unlock, lock lock

conn scott/tiger; //The password modification box pops up, and you can change the scott password

======

Forgot the password, modify the sys and system user passwords :

----Enter sqlplus for password reset----

sqlplus/as sysdba

null

alter user sys identified by 1234;   //Change the password of sys to 1234

conn sys/1234 as sysdba;     //Switch to sys

alter user system identified by 1234;//Change the passwords of other accounts in this way

===============================================

1. View all usernames

select username from dba_users; 

2. Delete the user and the table under the user

drop user username cascade; 

3. Find out the user's session:

SELECT SID, SERIAL# FROM V$SESSION WHERE USERNAME='SCOTT';

4. Kill the session of user SCOTT:

ALTER SYSTEM KILL SESSION 'SID, SERIAL#';

5.查看当前登录数据库的用户：

SELECT * FROM V$SESSION WHERE TYPE='USER';

6.查看所有用户信息

SELECT * FROM DBA_USERS

7.有时候需要导出某用户下的所有table、view、sequence、trigger等信息，下面的SQL可以将这些信息select出来：

select * from user_tables;

select * from user_views;

select * from user_sequences;

select * from user_triggers;

8.查看当前用户的默认表空间

　SQL>select username,default_tablespace from user_users;

9.查看当前用户的角色

　SQL>select * from user_role_privs;

10.查看当前用户的系统权限和表级权限

　SQL>select * from user_sys_privs;

　SQL>select * from user_tab_privs;

11.显示当前会话所具有的权限

　　SQL>select * from session_privs;

　 显示指定用户所具有的系统权限

　　SQL>select * from dba_sys_privs where grantee=’GAME’;

 

===============================================

二：

表空间

 

查看表空间

select * form v$tablespace;

 

查看表空间详细的数据文件

select file_name,tablespace_name from dba_data_files;

 

创建表空间（创建表空间的时候，指定多个数据文件，以逗号隔开：）

create tablespace  表空间名 datafile '路径+数据文件名1.dbf' size 50m

autoextend on next 10m maxsize unlimited；//数据文件自动扩容，开启自动扩展，一次扩展10m，表空间最大的大小是无限大

 

查看表空间是否为自动扩展

select tablespace_name,autoextensible from dba_data_files;

 

alter database datafile '路径+数据文件名' autoextend off;//取消自动扩展

alter database datafile '路径+数据文件名' autoextend on;//开启自动扩展

 

增加数据文件2

alter tablespace 表空间名 add datafile '路径+数据文件2.dbf' size 50m;

 

删除表空间,没有删除内部文件

drop tablespace 表空间名;

删除表空间，同时删除内部文件

drop tablespace 表空间名 including contants and datafiles;

 

===============================================

简化权限管理，引入了角色的概念，角色是具有名称的一组权限的组合

------常用系统预定义角色

1.CONNECT：临时用户

2.RESOURCE：更为可靠和正式的用户

3.DBA：数据库管理员角色，拥有管理数据库的最高权限

创建用户，并授权

 

一、创建用户的时候指定表空间

create user 新用户 identified by 密码 default tablespace 表空间;//创建用户,并给他指定默认使用的表空间

conn 新用户/密码;//此时连接不了

 

grant connect,resource to 新用户;//给新用户connect和resource的权限，再conn就可以连接了； 

 

 

二、给已存在的用户指定表空间

     alter user username default tablespace userspace;

 

===============================================

创建表：=teacher表=======

create table teacher

(tno number(4) not null,

tname varchar2(14) not null,

tid char(18),

gender char(2),

birthdate date);

 

查看表：

desc teacher;

 

更改表：

alter table teacher add (sal number(7,2),hiredate date,wechat varchar2(30));

alter table teacher modify（tname varchar2（30））；

alter table teacher drop column wechat；

更改列名：

alter table teacher rename column column to xingbie ；

 

 

edit，保存之后，/ 执行

 

增加主键：

alter table teacher add constraint pk_teacher 

primary key(tno);

 

增加唯一约束：

alter table teacher add constraint uk_teacher_tname unique(tname);

增加检查约束：

alter table teacher add constraint ck_teacher_gender 

check(gender in ('male','female'));

Add foreign key constraints:

alter table teacher add constraint fk_teacher_deptno_dept foreign key(deptno) 

references dept(deptno);

 

How does SQL relate tables and sequences

1: First create a sequence object

    CREATE SEQUENCE sq_num
       INCREMENT BY 1
       START WITH 1
       NOMAXVALUE
       NOCYCLE

2: When inserting a record, apply the sequence object on the primary key
   Suppose there is a customer table with a primary key bh, you can do this
   INSERT INTO customer
     VALUES( sq_num.NEXTVAL,'Zhang San',........)

CREATE SEQUENCE sq_name -- create a sequence

[start with n] [increment by n][ maxvalue n|nomaxvalue][cycle|nocycle][cache n|nocache]
;
sq_name.currval -- current sequence number
sq_name.nextval -- next sequence number
DROP SEQUENCE sq_name; -- delete Sequence ------------------------------------- 1. Create a sequence

CREATE SEQUENCE sq_teacher
       INCREMENT BY 1
       START WITH 1
       NOMAXVALUE
       NOCYCLE

2. To view the current sequence value (view it in the dummy table dual),     you must first initialize the sequence to view it as follows: first nextval (initialization) select sq_teacher.nextval from dual and then view select sq_currval from dual ----------- -------------------------------------------------- ---------- 1. First delete the sequence, then recreate it. But that's not the point of the present. This method is more convenient.
　　2. Modify the initial value by Increment By.
　　For example: if the sequence name is SeqTest2010_S, the initial value is 13, and now to set the initial value to 1020, the Increment By value is: 1007(1020-13)
　　2.1 Execute: Alter Sequence SeqTest2010_S Increment By 1007;
　　2.2 Execute: Select SeqTest2010_S.NextVal From Dual;
　　2.3 Execute: Alter Sequence SeqTest2010_S Increment By 1; The
　　modification is completed. Keep it simple --------------------------------------

 

number(3,1) 99.9

number (3,-1)990

number(2)  99

number 表示无限大

 

     提供四种类型的约束保证完整性

域完整性

实体完整性

引用完整性

自定义完整性