显示用户账号及信息

• MySQL 用户账号和信息存储在名为 mysql 的 MySQL 数据库中。 mysql 数据库中有一张名为 user 的表， 它包含所有用户账号。 user 表中有名为 user 的列，它存储的是用户登录名。

   mysql> use mysql;
  Database changed
  mysql>  select user,host from user;
  +------------------+-----------+
  | user             | host      |
  +------------------+-----------+
  | mysql.infoschema | localhost |
  | mysql.session    | localhost |
  | mysql.sys        | localhost |
  | root             | localhost |
  +------------------+-----------+
  4 rows in set (0.005 sec)
  
  mysql>
                                       

创建重命名及删除用户账号

• 创建名为 jj 的新用户账号：

  
     create user jj identified by 'happy';
                                  

  
    mysql>  create user jj identified by 'happy';
    Query OK, 0 rows affected (3.228 sec)
  
    mysql>
                                                 

  
    mysql> select user,host from user;
  +------------------+-----------+
  | user             | host      |
  +------------------+-----------+
  | jj               | %         |
  | mysql.infoschema | localhost |
  | mysql.session    | localhost |
  | mysql.sys        | localhost |
  | root             | localhost |
  +------------------+-----------+
  5 rows in set (0.006 sec)
  
  mysql>
       

  • host 为 % 允许任何主机访问； host 为 localhost 允许本地主机访问。

• 把用户名为 jj 的重新命名为 jjuni：

  
      rename user jj to jjuni;
                                  

  
  mysql> rename user jj to jjuni;
  Query OK, 0 rows affected (0.736 sec)
  
  mysql>
                                                 

  mysql> select user,host from user;
  +------------------+-----------+
  | user             | host      |
  +------------------+-----------+
  | jjuni            | %         |
  | mysql.infoschema | localhost |
  | mysql.session    | localhost |
  | mysql.sys        | localhost |
  | root             | localhost |
  +------------------+-----------+
  5 rows in set (0.006 sec)
  
  mysql>
  
       

• 删除用户账号

  
       drop user jjuni;