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Linux mysql 常用命令及问题解决方案 centos 安装 mysql yum install mysql yum install mysql-server yum install mysql-devel chgrp -R mysql /var/lib/mysql chmod -R 770 /var/lib/mysql 启动 service mysqld start 修改登录密码 mysql select user,host

Linux mysql 常用命令及问题解决方案

centos 安装 mysql

yum install mysql 

yum install mysql-server 

yum install mysql-devel 

chgrp -R mysql /var/lib/mysql 

chmod -R 770 /var/lib/mysql 

启动

service mysqld start

修改登录密码

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

mysql初始化

这进可能出现这个问题: mysql“Access denied for user 'root'@'localhost'”

解决mysql“Access denied for user 'root'@'localhost'”

# mysql -uroot -p 

Enter password:

ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: NO)

解决办法

First things first. Log in as root and stop the mysql daemon.

sudo /etc/init.d/mysql stop

Now lets start up the mysql daemon and skip the grant tables which store the passwords.

sudo mysqld_safe –skip-grant-tables&

(press Ctrl C now to disown the process and start typing commands again)

You should see mysqld start up successfully. If not, well you have bigger issues. Now you should be able to connect to mysql without a password.

sudo mysql –user=root mysql

update user set Password=PASSWORD('new-password'); flush privileges; exit;

Now kill your running mysqld then restart it normally.

sudo killall mysqld_safe& (press Ctrl C now to disown the process and start typing commands again) /etc/init.d/mysql start

You should be good to go. Try not to forget your password again.

# mysql -uroot -p

Enter password:

mysql> 

下面就是初始化了

mysqladmin -u root password ‘newpassword’ [引号内填密码] 

f、 让mysql数据库更安全 

mysql -u root -p [此时会要求你输入刚刚设置的密码,输入后回车即可 

mysql> DROP DATABASE test; [删除test数据库] 

mysql> DELETE FROM mysql.user WHERE user = ”; [删除匿名帐户] 

mysql> FLUSH PRIVILEGES; [重载权限] 

select host , user from user 

CentOS安装MySQL支持远程连接的方法

CentOS系统安装好MySQL后,默认情况下不支持用户通过非本机连接上数据库服务器,下面是解决方法: 

1、在控制台执行 mysql -u root -p mysql,系统提示输入数据库root用户的密码,输入完成后即进入mysql控制台,

这个命令的第一个mysql是执行命令,第二个mysql是系统数据名称,不一样的。

2、在mysql控制台执行 GRANT ALL PRIVILEGES ON *.* TO 'root'@'%' IDENTIFIED BY 'MyPassword' WITH GRANT OPTION;

3、在mysql控制台执行命令中的 'root'@'%' 可以这样理解: root是用户名,%是主机名或IP地址,这里的%代表任意主机或IP地址,

你也可替换成任意其它用户名或指定唯一的IP地址;'MyPassword'是给授权用户指定的登录数据库的密码;另外需要说明一点的

是我这里的都是授权所有权限,可以指定部分权限,GRANT具体操作详情见:http://dev.mysql.com/doc/refman/5.1/en/grant.html

4、不放心的话可以在mysql控制台执行 select host, user from user; 检查一下用户表里的内容,我的检查如下图所示:

关闭防火墙服务

#/etc/init.d/iptables stop

三.永久关闭防火墙

我们也可以永久的关闭防火墙,但是我不建议大家这样做.永久关闭防火墙可以这样: \ #chkconfig –level 35 iptables off

也可以直接修改

/etc/sysconfig/iptables

添加一条

-A RH-Firewall-1-INPUT -m state –state NEW -m tcp -p tcp –dport 80 -j ACCEPT

/etc/init.d/mysql start (stop) 为启动和停止服务器 /etc/mysql/ 主要配置文件所在位置 my.cnf /var/lib/mysql/ 放置的是数据库表文件夹,这里的mysql相当于windows下mysql的date文件夹

启动mysql后,以root登录mysql isher@isher-ubuntu:~$ mysql -u root

show variables like 'character%'; #执行编码显示

Variable_name Value

character_set_client latin1

character_set_connection latin1

character_set_database latin1

character_set_filesystem binary

character_set_results latin1

character_set_server latin1

character_set_system utf8

character_sets_dir /usr/share/mysql/charsets/

修改mysql默认数据库的编码

在某些时候,我们续要修改mysql默认数据库的编码,以保证某些迁移的程序可以正常显示,编辑my.cnf文件进行编码修改 

在linux下修改 /etc/mysql/my.cnf文件或者是/etc/my.cnf

找到客户端(可能没有,要自己手动添加)配置[client] 在下面添加 

default-character-set=utf8 默认字符集为utf8 

在找到[mysqld] 添加 

default-character-set=utf8 默认字符集为utf8 

init_connect='SET NAMES utf8' (设定连接mysql数据库时使用utf8编码,以让mysql数据库为utf8运行) 

修改好后,重新启动mysql 即可,查询一下show variables like 'character%'; 

Variable_name Value

character_set_client utf8

character_set_connection utf8

character_set_database utf8

character_set_filesystem binary

character_set_results utf8

character_set_server utf8

character_set_system utf8

character_sets_dir /usr/share/mysql/charsets/

最好还要配几个东西东西: old_passwords=1 

max_allowed_packet=16M 允许最大的包 

lower_case_table_names=1 大小写不敏感 

max_connections=200 最大连接数 


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