Mysql

来源：

问题的引出：

我在CentOS上装完mysql后，用navicat链接的时候，抛出MySql - SQL Error (1130): Host IP is not allowed to connect to this MySQL server 错误，具体解决方法请参考本人日志http://361324767.blog.163.com/blog/static/114902525201232832621498/。

该问题解决后，本人登录mysql ，输mysql -u root时无错，但是执行如下语句时：

mysql> use mysql

抛出该错误，参考网上各位大抄的大作如下：

如先输入mysql,成功启动后输入use mysql,出现如下错误：Access denied for user ''@'localhost' to database 'mysql'
还有，输mysql可以，输mysql -u root就出错了：
Access denied for user 'root'@'localhost' (using password: NO).
The reason is:
是昨日更新ROOT密码时出错
update user set password = '123456' where user ="root" //这样写是错的，密码其实不是123456
应该为update user set password = password ('123456') where user = "root"
具体操作步骤：
关闭mysql:
# service mysqld stop
然后:
# mysqld_safe --skip-grant-tables
启动mysql:
# service mysqld start
mysql -u root
mysql> use mysql
mysql> UPDATE user SET Password=PASSWORD('xxx') WHERE user='root';
mysql> flush privileges;
mysql>q