Linux（CentOS）下，安装MySQL

# yum install -y mysql-devel
# yum install -y mysql-server
# yum install -y mysql
# chgrp -R mysql /var/lib/mysql
# chmod -R 770 /var/lib/mysql
# service mysqld start 
MySQL Daemon failed to start.
如果启动失败，可以用下面的命令，查看失败原因：
# less /var/log/mysqld.log
发现如下的错误提示：
InnoDB: auto-extending data file ./ibdata1 is of a different size 640 pages (rounded down to MB) 
than specified in the .cnf file: initial 768 pages, max 0 (relevant if non-zero) pages!
修改配置文件中的值（640/64=10M）并查看修改结果：
# vi /etc/my.cnf
innodb_data_file_path = ibdata1:10M:autoextend
# du -sm /var/lib/mysql/ibdata1 
10      /var/lib/mysql/ibdata1
设置开机自启动，并查看设置结果：
# chkconfig mysqld on
# chkconfig mysqld --list
mysqld          0:off   1:off   2:on    3:on    4:on    5:on    6:off
创建根用户密码，并登陆测试：
# mysqladmin -u root password 123456 #//然后输入新密码，并确认一次
# mysql -u root -p

忘记密码时，可用如下方法重置：
# service mysqld stop
# mysqld_safe --user=root --skip-grant-tables --skip-networking &
# mysql -u root 
mysql> use mysql;
mysql> update user set password=password("new_password") where user="root"; 
mysql> flush privileges;

远程登陆的授权：

mysql> GRANT ALL PRIVILEGES ON *.* TO 'root'@'%' IDENTIFIED BY 'password' WITH GRANT OPTION;
远程登陆的授权成功后，可以用如下命令查看，如果有host为%的项，说明是OK的。

mysql> select host,user,password from user;
+-----------+------+-------------------------------------------+
| host      | user | password                                  |
+-----------+------+-------------------------------------------+
| localhost | root | *6C1C7AE8E372FE12E3DE2E22FE6C04CF8F6737DA |
| 127.0.0.1 | root | *6C1C7AE8E372FE12E3DE2E22FE6C04CF8F6737DA |
| ::1       | root | *6C1C7AE8E372FE12E3DE2E22FE6C04CF8F6737DA |
| localhost |      |                                           |
| %         | root | *6C1C7AE8E372FE12E3DE2E22FE6C04CF8F6737DA |
+-----------+------+-------------------------------------------+
5 rows in set (0.00 sec)