背景：
长时间的对着电脑，造成了"神志不清"，一不小心在Mysql下误操作了“revoke all on *.* from 'root'@'localhost'; ”，这个命令的意思就是删除mysql中最高权限的用户root的所有权限。因为本机mysql的密码为空，虽然依旧可以进去mysql，但再也不法执行修改操作。
解决方法：
1、首先杀掉mysql进程
#pkill mysql
2、以--skip-grant-tables方式启动
#/usr/local/mysql/bin/mysqld_safe --user mysql --skip-grant-tables&
3、更新的MYSQL.USER表的所有字段中为N的为Y
# /usr/local/mysql/bin/mysql 进入mysql
>use mysql;update user set Select_priv ='Y' where user = 'root';
update user set Insert_priv ='Y' where user = 'root';
update user set Update_priv ='Y' where user = 'root';
update user set Delete_priv ='Y' where user = 'root';
update user set Create_priv ='Y' where user = 'root';
update user set Drop_priv ='Y' where user = 'root';
update user set Reload_priv ='Y' where user = 'root';
update user set Shutdown_priv ='Y' where user = 'root';
update user set Process_priv ='Y' where user = 'root';
update user set File_priv ='Y' where user = 'root';
update user set Grant_priv ='Y' where user = 'root';
update user set References_priv ='Y' where user = 'root';
update user set Index_priv ='Y' where user = 'root';
update user set Alter_priv ='Y' where user = 'root';
update user set Show_db_priv ='Y' where user = 'root';
update user set Super_priv ='Y' where user = 'root';
update user set Create_tmp_table_priv ='Y' where user = 'root';
update user set Lock_tables_priv ='Y' where user = 'root';
update user set Execute_priv ='Y' where user = 'root';
update user set Repl_slave_priv ='Y' where user = 'root';
update user set Repl_client_priv ='Y' where user = 'root';
update user set Create_view_priv ='Y' where user = 'root';
update user set Show_view_priv ='Y' where user = 'root';
update user set Create_routine_priv ='Y' where user = 'root';
update user set Alter_routine_priv ='Y' where user = 'root';
update user set Create_user_priv ='Y' where user = 'root';
update user set Event_priv ='Y' where user = 'root';
update user set Trigger_priv ='Y' where user = 'root';
总结：
权限问题最后要保证“mysql.user”表中 host为“localhost”和“%”都有root的所有权限。
host列是指定登录的ip，比如说 user=root host=192.168.1.1 ，这里的意思就是说，root用户只能通过 192.168.1.1的客户端去访问，而%则是个通配符， 如果host=192.168.1.%，那么就表示 只要是 ip为host=192.168.1.前缀的客户端都可以连接，那么host=%的话则表示所有ip都有权去连接，这也就是为什么在开启远程连接的时候，大部分人都直接把host改成%的缘故，因为省事。
本文出自 “Just For Fun!” 博客，请务必保留此出处http://linuxnote.blog.51cto.com/9876511/1641488