创建用户: 

CREATE USER 'username'@'host' IDENTIFIED BY 'password'; 


用户删除：

DROP USER 'username'@'host';


创建用户并授权：

GRANT privileges ON databasename.tablename TO 'username'@'host' IDENTIFIED BY 'password' ;

用授权户：

GRANT privileges ON databasename.tablename TO 'username'@'host';


撤销用户权限：

REVOKE privileges ON databasename.tablename FROM 'username'@'host';


用户访问权限更改：

UPDATE mysql.user SET host = 'host'  WHERE user ='root';