今天在测试集群用的mysql上，遇到个权限的问题：
SQLException : SQL state: 42000 com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Access denied for user 'root'@'%' to database 'ranger' ErrorCode: 1044
我是以root用户登录mysql的，怎么还会遇到这问题呢，有点猫腻，我查看了下mysql下user表的各用户的权限信息
mysql> SELECT host,user,password,Grant_priv,Super_priv FROM mysql.user;
+--------------+---------+-------------------------------------------+------------+------------+
| host | user | password | Grant_priv | Super_priv |
+--------------+---------+-------------------------------------------+------------+------------+
| 192.168.28.% | oozie | *FED29C14B2E900D70B11B1F1B370F953BA51A6A0 | N | Y |
| 192.168.28.% | hive | *FED29C14B2E900D70B11B1F1B370F953BA51A6A0 | N | Y |
| 192.168.28.% | root | *FED29C14B2E900D70B11B1F1B370F953BA51A6A0 | Y | Y |
| localhost | ranger | *84BB87F6BF7F61703B24CE1C9AA9C0E3F2286900 | N | N |
| localhost | root | 0 | Y | Y |
| % | root | *FED29C14B2E900D70B11B1F1B370F953BA51A6A0 | N | Y |
| 127.0.0.1 | root | *FED29C14B2E900D70B11B1F1B370F953BA51A6A0 | Y | Y |
| % | ranger | *84BB87F6BF7F61703B24CE1C9AA9C0E3F2286900 | N | Y |
+--------------+---------+-------------------------------------------+------------+------------+可以看到授权的权限没有打开： Grant_priv is set to N for root@%. 修复下
UPDATE mysql.user SET Grant_priv='Y', Super_priv='Y' WHERE User='root';
FLUSH PRIVILEGES;
重新登录下，就ok了。如果不能执行update的话，那就先停下mysql服务，然后mysqld_safe --skip-grant-table & (这个可以参考之前文章：http://blog.csdn.net/oDaiLiDong/article/details/50196661)，等改完之后再正常启动mysql
