今天帮朋友设计了几张数据库表，安装mysql后启动出现报错：
[root@www lib]# service mysqld start
mysqld: unrecognized service
[root@www lib]# /etc/init.d/mysql start
bash: /etc/init.d/mysql: No such file or directory
然后百度了一下，发现自己好弱智啊，现把原文转载如下，给自己记录下来，如果大家以后也碰到此问题，也给大家提供一个参考，原文如下。
在Centos中用命令 yum install mysql安装数据库，但装完后运行mysqld启动mysql的时候提示找不到，通过 find / | grep mysqld 也没找到mysqld的目录，后来在Google上搜索下，才知道用yum安装时候mysql也有三个参数的。
yum install mysql，只是安装了mysql的client，如果你只安装了这一步，就会发现找不到mysqld。
yum install mysql-server，才安装了mysql的服务后台程序；当然还有一个MySQL-devel。
装上后就有mysqld了。
具体步骤如下：
yum install mysql
yum install mysql-server
yum install mysql-devel
chgrp -R mysql /var/lib/mysql
chmod -R 770 /var/lib/mysql
service mysqld start
To start mysqld at boot time you have to copy
support-files/mysql.server to the right place for your system
PLEASE REMEMBER TO SET A PASSWORD FOR THE MySQL root USER !
To do so, start the server, then issue the following commands:
/usr/bin/mysqladmin -u root password 'new-password'
/usr/bin/mysqladmin -u root -h LAMP.ORG password 'new-password'
Alternatively you can run:
/usr/bin/mysql_secure_installation
which will also give you the option of removing the test
databases and anonymous user created by default. This is
strongly recommended for production servers.
See the manual for more instructions.
You can start the MySQL daemon with:
cd /usr ; /usr/bin/mysqld_safe &
You can test the MySQL daemon with mysql-test-run.pl
cd mysql-test ; perl mysql-test-run.pl
Please report any problems with the /usr/bin/mysqlbug script!
The latest information about MySQL is available on the web at
http://www.mysql.com
Support MySQL by buying support/licenses at http://shop.mysql.comz
