service mysql start出错，mysql启动不了，解决mysql: unrecognized service错误的方法如下：

[root@90jianzhi.cn ~]# service mysql start
mysql: unrecognized service
[root@90jianzhi.cn ~]# service mysql restart
mysql: unrecognized service

[root@90jianzhi.cn ~]# rpm -q mysql 查询发现mysql已经正常安装
mysql-5.1.52-jason.1

[root@90jianzhi.cn ~]# /etc/rc.d/init.d/mysqld start 直接启动没问题
Starting mysqld: [ OK ]

[root@90jianzhi.cn ~]# ls /etc/rc.d/init.d/mysqld -l
-rwxr-xr-x 1 root root 5509 Dec 18 02:31 /etc/rc.d/init.d/mysqld

[root@90jianzhi.cn ~]# chkconfig mysqld on 设置mysql开机启动

[root@90jianzhi.cn ~]# chmod 755 /etc/rc.d/init.d/mysqld 修改mysqld执行权限

[root@90jianzhi.cn ~]# service mysqld start 搞定

Starting mysqld: [ OK ]
[root@90jianzhi.cn ~]# service mysqld start
Starting mysqld: [ OK ]
[root@90jianzhi.cn ~]# service mysqld status
mysqld (pid 9487) is running...