mysqladmin -uroot password 'newpassword';

//创建了一个名为：jeecn  密码为：jeecn  的用户。
mysql> insert into mysql.user(Host,User,Password) values(‘localhost’,'jeecn’,password(‘jeecn’));
//或者
//create user jeecn;
//update user set Password = PASSWORD("jeecn") where user='jeecn';
 //刷新系统权限表
mysql>flush privileges;

mysql>grant all privileges on testdb.* to jeecn@localhost identified by 'jeecn';
 //刷新系统权限表
mysql>flush privileges

//grant 权限1,权限2,…权限n on 数据库名称.表名称 to 用户名@用户地址 identified by ‘连接口令’;
//权限n代表select,insert,update,delete,create,drop,index,alter,grant,references,reload,shutdown,process,file等14个权限

revoke all on *.* from dba@localhost;  

show grants;