Centos5下构建 MySQL服务器和常见问题解决办法

当前的数据库种类比较多，有MS-SQL，Oracle，MYSQL，POSTGRESQL等，而MYSQL在LAMP架构中的份量是举足轻重的，下面就来介绍下Centos5下MySQL的安装和基本配置。

使用yum安装MySQL（在LAMP架构中，开始安装mysql之前应该先安装apache和php）
[root@centos5 /]# yum -y install mysql-server
Loading "fastestmirror" plugin
Loading mirror speeds from cached hostfile
* base: centos.candishosting.com.cn
* updates: mirror.khlug.org
* addons: centos.candishosting.com.cn
* extras: centos.candishosting.com.cn
Setting up Install Process
Parsing package install arguments
Resolving Dependencies
--> Running transaction check
---> Package mysql-server.i386 0:5.0.45-7.el5 set to be updated
--> Processing Dependency: libmysqlclient.so.15(libmysqlclient_15) for package: mysql-server
--> Processing Dependency: perl-DBD-MySQL for package: mysql-server
--> Processing Dependency: libmysqlclient_r.so.15(libmysqlclient_15) for package: mysql-server
--> Processing Dependency: libmysqlclient_r.so.15 for package: mysql-server
--> Processing Dependency: mysql = 5.0.45-7.el5 for package: mysql-server
--> Processing Dependency: libmysqlclient.so.15 for package: mysql-server
--> Running transaction check
---> Package perl-DBD-MySQL.i386 0:3.0007-1.fc6 set to be updated
---> Package mysql.i386 0:5.0.45-7.el5 set to be updated
--> Finished Dependency Resolution

Dependencies Resolved

=============================================================================
Package                 Arch       Version          Repository        Size
=============================================================================
Installing:
mysql-server            i386       5.0.45-7.el5     base              9.7 M
Installing for dependencies:
mysql                   i386       5.0.45-7.el5     base              4.1 M
perl-DBD-MySQL          i386       3.0007-1.fc6     base              147 k

Transaction Summary
=============================================================================
Install      3 Package(s)
Update       0 Package(s)
Remove       0 Package(s)

Total download size: 14 M
Downloading Packages:
(1/3): mysql-5.0.45-7.el5 100% |=========================| 4.1 MB    02:57
(2/3): mysql-server-5.0.4 100% |=========================| 9.7 MB    07:19
(3/3): perl-DBD-MySQL-3.0 100% |=========================| 147 kB    00:07
Running rpm_check_debug
Running Transaction Test
Finished Transaction Test
Transaction Test Succeeded
Running Transaction
Installing: mysql                        ######################### [1/3]
Installing: perl-DBD-MySQL               ######################### [2/3]
Installing: mysql-server                 ######################### [3/3]

Installed: mysql-server.i386 0:5.0.45-7.el5
Dependency Installed: mysql.i386 0:5.0.45-7.el5 perl-DBD-MySQL.i386 0:3.0007-1.fc6
Complete!

安装PHP访问MySQL数据库的工具“php-mysql”

[root@centos5 ~]# yum -y install php-mysql
Loading "fastestmirror" plugin
Loading mirror speeds from cached hostfile
* base: centos.candishosting.com.cn
* updates: mirror.khlug.org
* addons: centos.candishosting.com.cn
* extras: centos.candishosting.com.cn
Setting up Install Process
Parsing package install arguments
Resolving Dependencies
--> Running transaction check
---> Package php-mysql.i386 0:5.1.6-20.el5_2.1 set to be updated
--> Processing Dependency: php-pdo for package: php-mysql
--> Running transaction check
---> Package php-pdo.i386 0:5.1.6-20.el5_2.1 set to be updated
--> Finished Dependency Resolution

Dependencies Resolved

=============================================================================
Package                 Arch       Version          Repository        Size
=============================================================================
Installing:
php-mysql               i386       5.1.6-20.el5_2.1 updates            84 k
Installing for dependencies:
php-pdo                 i386       5.1.6-20.el5_2.1 updates            62 k

Transaction Summary
=============================================================================
Install      2 Package(s)
Update       0 Package(s)
Remove       0 Package(s)

Total download size: 146 k
Downloading Packages:
(1/2): php-pdo-5.1.6-20.e 100% |=========================| 62 kB    00:20
(2/2): php-mysql-5.1.6-20 100% |=========================| 84 kB    00:11
Running rpm_check_debug
Running Transaction Test
Finished Transaction Test
Transaction Test Succeeded
Running Transaction
Installing: php-pdo                      ######################### [1/2]
Installing: php-mysql                    ######################### [2/2]

Installed: php-mysql.i386 0:5.1.6-20.el5_2.1
Dependency Installed: php-pdo.i386 0:5.1.6-20.el5_2.1
Complete!

[root@centos5 ~]# vi /etc/my.cnf （编辑mysql配置文件）

[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
user=mysql
# Default to using old password format for compatibility with mysql 3.x
# clients (those using the mysqlclient10 compatibility package).
old_passwords=1
default-character-set = utf8 （添加这一行，让MySQL的默认编码为UTF-8）

[mysqld_safe]
log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid
[mysql]
default-character-set = utf8 （添加这一行，设置mysql在安全模式启动后的默认编码为UTF-8）

[root@centos5 ~]# chkconfig mysqld on （设置mysql在开机后自动启动）
[root@centos5 ~]# chkconfig --list mysqld
mysqld          0:off   1:off   2:on    3:on    4:on    5:on    6:off

[root@centos5 ~]# /etc/rc.d/init.d/mysqld start       （启动mysql服务）

Initializing MySQL database: Installing MySQL system tables...
OK
Filling help tables...
OK

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'  

（在这里系统提示可以使用mysqladmin为root，localhost和root，centos5设置密码，centos5是我的主机名，可使用这个命令的时候系统却报错了！）
/usr/bin/mysqladmin -u root -h centos5 password 'new-password'
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.com
                                                           [ OK ]
Starting MySQL:                                            [ OK ]

[root@centos5 /]# netstat -ntpl |grep mysqld
tcp        0      0 0.0.0.0:3306                0.0.0.0:*                   LIST                                             EN      8168/mysqld

[root@centos5 /]# mysql -u root -p （正如前面提到的报错，在这里是因为root这个mysql用户已经有非空的密码存在了。）
Enter password:
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: NO)

（在这里我在Internet上搜索到了一个解决的办法）

[root@centos5 /]# /etc/rc.d/init.d/mysqld stop （先停止mysql服务）
Stopping MySQL:                                            [ OK ]

[root@centos5 /]# mysqld_safe --user=mysql --skip-grant-tables --skip-networking&（重新启动mysql服务的时候加上这些参数，这些参数具体代表了什么，我也不明白，大概是设置启动服务的时候跳过验证密码的表和网络吧！）
[1] 8850
Starting mysqld daemon with databases from /var/lib/mysql

[root@centos5 /]# /etc/rc.d/init.d/mysqld status
mysqld (pid 8902) is running...
[root@centos5 /]# mysql -u root
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 1
Server version: 5.0.45 Source distribution

Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

mysql>   （果然这次不用输入密码就可以进来了，也没有什么报错信息）

mysql> select user,host,password from mysql.user; (查看系用户表，果然localhost，root真的有密码，其他的两个都没有，如果用另外两个root用户登陆应该就不会出现之前的问题了)
+------+-----------+------------------+
| user | host      | password         |
+------+-----------+------------------+
| root | localhost | 7a3310dc39c1d3df |
| root | centos5   |                  |
| root | 127.0.0.1 |                  |
+------+-----------+------------------+
3 rows in set (0.01 sec)

mysql> UPDATE user SET Password=PASSWORD('123') where USER='root'; （接下来当然要修改下密码啦，这里就简单的设置成123）
Query OK, 3 rows affected (0.00 sec)
Rows matched: 3 Changed: 3 Warnings: 0

mysql> show databases; （查看下当前的数据库）
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| test               |
+--------------------+
3 rows in set (0.01 sec)

[root@centos5 /]# /etc/rc.d/init.d/mysqld stop （停止mysql服务）
STOPPING server from pid file /var/run/mysqld/mysqld.pid
090201 09:23:00 mysqld ended

Stopping MySQL:                                            [ OK ]
[1]+ Done                    mysqld_safe --user=mysql --skip-grant-tables --skip-networking

[root@centos5 /]# /etc/rc.d/init.d/mysqld start （以正常的方式启动服务）
Starting MySQL:                                            [ OK ]

[root@centos5 /]# mysql -u root -p （输入密码123登陆）
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 3
Server version: 5.0.45 Source distribution

Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

mysql> select user,host from mysql.user; （查看用户，并删除另外的两个root用户）
+------+-----------+
| user | host      |
+------+-----------+
| root | 127.0.0.1 |
| root | centos5   |
| root | localhost |
+------+-----------+
3 rows in set (0.00 sec)

mysql> delete from mysql.user where user='root' and host='127.0.0.1';
Query OK, 0 rows affected (0.01 sec)

mysql> delete from mysql.user where user='root' and host='centos5';
Query OK, 1 row affected (0.01 sec)

mysql> select user,host from mysql.user;
+------+-----------+
| user | host      |
+------+-----------+
| root | localhost |
+------+-----------+
1 row in set (0.00 sec)
mysql> exit
Bye

重新启动一次HTTP服务，让php-mysql反映到HTTP服务中
[root@centos5 /]# /etc/rc.d/init.d/httpd restart   
Stopping httpd:                                            [ OK ]
Starting httpd:                                            [ OK ]

本实验以此网页http://www.centospub.com/make/mysql.html为指导！mysql其他的基本操作可参考这个网页

5月2日，出现的错误及解决办法！

今天拿台新的VMware，使用yum安装完了mysql服务，启动的时候却出现了如下错误
[root@centos5 ~]# service mysqld start
Timeout error occurred trying to start MySQL Daemon.
Starting MySQL:                                            [FAILED]

于是查看了下日志信息，似乎是因为mysql.host文件不存在引起的
[root@centos5 ~]# tail -f /var/log/mysqld.log
090502 20:05:26 mysqld started
090502 20:05:26 InnoDB: Started; log sequence number 0 43655
090502 20:05:26 [ERROR] Fatal error: Can't open and lock privilege tables: Table 'mysql.host' doesn't exist
090502 20:05:26 mysqld ended

在网上找到了解决的办法，具体如下：
[root@centos5 ~]# /usr/bin/mysql_install_db --user=mysql
Installing MySQL system tables...
OK
Filling help tables...
OK

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 centos5 password 'new-password'
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.com

启动下mysql服务，这次可以正常启动了！
[root@centos5 ~]# service mysqld start
Starting MySQL:                                            [ OK ]

再次查看下日志
[root@centos5 /]# tail -f /var/log/mysqld.log
090502 20:05:26 mysqld started
090502 20:05:26 InnoDB: Started; log sequence number 0 43655
090502 20:05:26 [ERROR] Fatal error: Can't open and lock privilege tables: Table 'mysql.host' doesn't exist
090502 20:05:26 mysqld ended

090502 20:10:16 mysqld started
090502 20:10:16 InnoDB: Started; log sequence number 0 43655
090502 20:10:17 [Note] /usr/libexec/mysqld: ready for connections.
Version: '5.0.45' socket: '/var/lib/mysql/mysql.sock' port: 3306 Source distribution
A mysqld process already exists at Sat May 2 20:10:39 CST 2009

查看3306端口是否开启
[root@centos5 /]# netstat -ntpl |grep 3306
tcp        0      0 0.0.0.0:3306                0.0.0.0:*                   LISTEN      3473/mysqld

重启下mysql服务，看是否能正常运行
[root@centos5 /]# service mysqld restart
Stopping MySQL:                                            [ OK ]
Starting MySQL:
                                            [ OK ]
最后，登陆试下！
[root@centos5 /]# mysql -u root -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 3
Server version: 5.0.45 Source distribution

Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

mysql>