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

# service mysql start
mysql: unrecognized service
# service mysql restart
mysql: unrecognized service

# rpm -q mysql 查询发现mysql已经正常安装
mysql-5.1.52-jason.1

# /etc/rc.d/init.d/mysqld start 直接启动没问题
Starting mysqld: [ OK ]

# 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

# chkconfig mysqld on 设置mysql开机启动

# chmod 755 /etc/rc.d/init.d/mysqld 修改mysqld执行权限

# service mysqld start 搞定
Starting mysqld: [ OK ]
# service mysqld start
Starting mysqld: [ OK ]
# service mysqld status
mysqld (pid 9487) is running...