关系型数据库sql语句

关系型数据库sql语句

关系型数据库mysql SQL语句数据库管理操作。

1.创建用户（create user）:
语法(syntax)：

     create user 'username'@'host' identified by 'password'

 例子(example):

     >create user 'shine'@'localhost' identified by '111111';  #本地登陆用户
     >create user 'shine'@'192.168.2.101' identified by '111111';  # 指定ip地址用户：
     >create user 'shine'@'%' identified by '111111';   # 任意地址用户：
     >create user 'shine'@'%' identified by ''; #任意地址无密码用户
     >create user 'shine'@'%';  #同上
     >create user shine; #同上

2.授权（grant）：
语法（syntax）：

     grant privilege1 [,privilege [, privilege] ...] on databaseName.tableName to username@hostname/IP identified by 'password' privilege: select, insert, update, delete, create, drop, index, alter, grant, references, reload, shutdown, process, file and so on fourteen privileges.

例子(example):

>grant select, insert, update, delete, create, drop on demo.user to shine@192.168.2.101 identified by '111111';

给地址为192.168.2.101的shine用户赋予在数据库demo表user上select, insert, update, delete, create, drop权限，使用口令111111

>grant all privileges on demo.* to shine@192.168.2.101 identified by '111111';

给地址为192.168.2.101的shine用户赋予在数据库demo上所有表上的所有权限，使用口令111111.

>grant all privileges on *.* to shine@% identified by '111111'

给shine用户赋予在所有数据库上所有表上的所有权限，使用口令111111.
3. 直接向mysql.user表插入数据

>insert into user (host, user, password) values('%', 'shine', password('111111'));

4.刷新系统权限

>flush privileges;

5.修改mysql用户密码方式

• 使用mysqladmin：

     syntax：
      mysqladmin -u  username -p oldpassword password newpassword
      example:
      mysqladmin -u shine -p 111111 password 123456

• 修改user表的用户key：

     syntax:
      update mysql.user set password=password('newpasswd') where User="username" and Host="IP";
      example:
      update user set password=password('111111') where user='shine';
      flush privileges;

• 使用set password 语句修改密码：

      syntax:
      set password for 'username'@'host' = password('newpassword');
      set password = password('newpassword') #仅限于修改自身 example： set password for 'shine'@'192.168.2.101'=password('111111');

6.删除用户和撤销用户权限

• 取消一个用户和其权限：

 syntax:
    drop user username;
    example:
    drop user shine@'%';
    drop user shine@'localhost';

• 撤销用户权限：

    syntax：
    revoke privilege on databasename.tablename from 'username'@'host';
    example:
    revoke select on *.* from 'shine'@'%';
    revoke update on demo.user from 'shine'@'%';
    revoke all on *.* from 'shine'@'%';

• 查看权限用户权限：

  syntax:
    show grants for 'username'@'hostname/IP';
    example:
    show grants for 'shine'@'192.168.2.101';

• 删除用户：

    syntax:
    delete from user where user = "username" and host="hostname/IP";
    example:
    delete from user where user = "shine" and host='192.168.2.101';

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