一、系统环境

  yum update升级以后的系统版本为

  

`[root@yl-web yl]# cat /etc/redhat-release 
CentOS Linux release 7.1.1503 (Core) `

  二、mysql安装

  一般网上给出的资料都是

   #yum install mysql

    #yum install mysql-server

  安装mysql和mysql-devel都成功，但是安装mysql-server失败，如下：

   [root@yl-web yl]# yum install mysql-server

    Loaded plugins: fastestmirror
    Loading mirror speeds from cached hostfile
     * base: mirrors.sina.cn
     * extras: mirrors.sina.cn
     * updates: mirrors.sina.cn
    No package mysql-server available.

  查资料发现是CentOS 7 版本将MySQL数据库软件从默认的程序列表中移除，用mariadb代替了。

  有两种解决办法：

  1、方法一：安装mariadb

  MariaDB数据库管理系统是MySQL的一个分支，主要由开源社区在维护，采用GPL授权许可。开发这个分支的原因之一是：甲骨文公司收购了MySQL后，有将MySQL闭源的潜在风险，因此社区采用分支的方式来避开这个风险。MariaDB的目的是完全兼容MySQL，包括API和命令行，使之能轻松成为MySQL的代替品。

  安装mariadb，大小59 M。

  [root@yl-web yl]# yum install mariadb-server mariadb

  mariadb数据库的相关命令是：

  systemctl start mariadb #启动MariaDB

  systemctl stop mariadb #停止MariaDB

  systemctl restart mariadb #重启MariaDB

  systemctl enable mariadb #设置开机启动

  所以先启动数据库

  [root@yl-web yl]# systemctl start mariadb

  然后就可以正常使用mysql了

   [root@yl-web yl]# mysql -u root -p

    Enter password: 
    Welcome to the MariaDB monitor.  Commands end with ; or \g.
    Your MariaDB connection id is 3
    Server version: 5.5.41-MariaDB MariaDB Server
    Copyright (c) 2000, 2014, Oracle, MariaDB Corporation Ab and others.
    Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
    MariaDB [(none)]> show databases;
    +--------------------+
    | Database           |
    +--------------------+
    | information_schema |
    | mysql              |
    | performance_schema |
    | test               |
    +--------------------+
    4 rows in set (0.00 sec)

  安装mariadb后显示的也是MariaDB [(none)]>，可能看起来有点不习惯。下面是第二种方法。

  2、方法二：官网下载安装mysql-server

   # wget http://dev.mysql.com/get/mysql-community-release-el7-5.noarch.rpm

    # rpm -ivh mysql-community-release-el7-5.noarch.rpm

  安装成功后重启mysql服务。

  # service mysqld restart

  初次安装mysql，root账户没有密码。

   [root@yl-web yl]# mysql -u root

    Welcome to the MySQL monitor.  Commands end with ; or \g.
    Your MySQL connection id is 3
    Server version: 5.6.26 MySQL Community Server (GPL)
    Copyright (c) 2000, 2015, Oracle and/or its affiliates. All rights reserved.
    Oracle is a registered trademark of Oracle Corporation and/or its
    affiliates. Other names may be trademarks of their respective
    owners.
    Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
    mysql> show databases;
    +--------------------+
    | Database           |
    +--------------------+
    | information_schema |
    | mysql              |
    | performance_schema |
    | test               |
    +--------------------+
    4 rows in set (0.01 sec)

  设置密码

   mysql> set password for 'root'@'localhost' =password('password');

    Query OK, 0 rows affected (0.00 sec)

  不需要重启数据库即可生效。

  在mysql安装过程中如下内容：

   Installed:

      mysql-community-client.x86_64 0:5.6.26-2.el7                mysql-community-devel.x86_64 0:5.6.26-2.el7                
      mysql-community-libs.x86_64 0:5.6.26-2.el7                  mysql-community-server.x86_64 0:5.6.26-2.el7               
    Dependency Installed:
      mysql-community-common.x86_64 0:5.6.26-2.el7                                                                            
    Replaced:
      mariadb.x86_64 1:5.5.41-2.el7_0          mariadb-devel.x86_64 1:5.5.41-2.el7_0   mariadb-libs.x86_64 1:5.5.41-2.el7_0  

  所以安装完以后mariadb自动就被替换了，将不再生效。

   [root@yl-web yl]# rpm -qa |grep mariadb

  三、配置mysql 1、编码

  mysql配置文件为/etc/my.cnf

  最后加上编码配置

   [mysql]

  这里的字符编码必须和/usr/share/mysql/charsets/Index.xml中一致。

  mysql初始password_mysql初始password_初始化

  2、远程连接设置

  把在所有数据库的所有表的所有权限赋值给位于所有IP地址的root用户。

  mysql> grant all privileges on . to root@'%'identified by 'password';

  如果是新用户而不是root，则要先新建用户

  mysql>create user 'username'@'%' identified by 'password';

  此时就可以进行远程连接了。

  Mariadb修改root密码

  默认情况下，新安装的 mariadb 的密码为空，在shell终端直接输入 mysql 就能登陆数据库。

  如果是刚安装第一次使用，请使用 mysql_secure_installation 命令初始化。

  

`# mysql_secure_installation
NOTE: RUNNING ALL PARTS OF THIS SCRIPT IS RECOMMENDED FOR ALL MariaDB
  SERVERS IN PRODUCTION USE!  PLEASE READ EACH STEP CAREFULLY!
In order to log into MariaDB to secure it, we'll need the current
password for the root user.  If you've just installed MariaDB, and
you haven't set the root password yet, the password will be blank,
so you should just press enter here.
Enter current password for root (enter for none):
OK, successfully used password, moving on...
Setting the root password ensures that nobody can log into the MariaDB
root user without the proper authorisation.
Set root password? [Y/n] y
New password:
Re-enter new password:
Password updated successfully!
Reloading privilege tables..
 ... Success!
By default, a MariaDB installation has an anonymous user, allowing anyone
to log into MariaDB without having to have a user account created for
them.  This is intended only for testing, and to make the installation
go a bit smoother.  You should remove them before moving into a
production environment.
Remove anonymous users? [Y/n] y
 ... Success!
Normally, root should only be allowed to connect from 'localhost'.  This
ensures that someone cannot guess at the root password from the network.
Disallow root login remotely? [Y/n] y
 ... Success!
By default, MariaDB comes with a database named 'test' that anyone can
access.  This is also intended only for testing, and should be removed
before moving into a production environment.
Remove test database and access to it? [Y/n] y
  • Dropping test database...
     ... Success!
  • Removing privileges on test database...
     ... Success!
Reloading the privilege tables will ensure that all changes made so far
will take effect immediately.
Reload privilege tables now? [Y/n] y
 ... Success!
Cleaning up...
All done!  If you've completed all of the above steps, your MariaDB
installation should now be secure.
Thanks for using MariaDB!`

  这里针对的是知道 root 密码，而需要修改的情况。

  两种修改方法：

  1、直接在shell命令行使用 mysqladm 命令修改。

  

`# mysqladmin -uroot -poldpassword password newpassword
这种方法的弊端在于会明文显示密码。`

  2、登陆数据库修改密码。

  

`# mysql -uroot -p
2.1 更新 mysql 库中 user 表的字段：
MariaDB [(none)]> use mysql;  
MariaDB [mysql]> UPDATE user SET password=password('newpassword') WHERE user='root';  
MariaDB [mysql]> flush privileges;  
MariaDB [mysql]> exit;
2.2 或者，使用 set 指令设置root密码：
MariaDB [(none)]> SET password for 'root'@'localhost'=password('newpassword');  
MariaDB [(none)]> exit; `

  如果是忘记了 root 密码，则需要以跳过授权的方式启动 mariadb 来修改密码。

  1、先停掉服务。

  

# systemctl stop mariadb

  2、使用跳过授权的方式启动 mariadb。

  

`# mysqld_safe --skip-grant-tables &
[1] 1441
[root@centos7 ~]# 170531 02:10:28 mysqld_safe Logging to '/var/log/mariadb/mariadb.log'.
170531 02:10:28 mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql
ps -ef | grep 1441
root      1441   966  0 02:10 pts/0    00:00:00 /bin/sh /usr/bin/mysqld_safe --skip-grant-tables
mysql     1584  1441  0 02:10 pts/0    00:00:00 /usr/libexec/mysqld --basedir=/usr --datadir=/var/lib/mysql --plugin-dir=/usr/lib64/mysql/plugin --user=mysql --skip-grant-tables --log-error=/var/log/mariadb/mariadb.log --pid-file=/var/run/mariadb/mariadb.pid --socket=/var/lib/mysql/mysql.sock`

  3、当跳过授权启动时，可以不需要密码直接登陆数据库。登陆更新密码即可。

  

`# mysql
MariaDB [(none)]> use mysql;  
MariaDB [mysql]> UPDATE user SET password=password('newpassword') WHERE user='root';  
MariaDB [mysql]> flush privileges;   
MariaDB [mysql]> exit; 
更新密码后，在跳过授权启动时也不能空密码直接登陆了。`

  4、关闭跳过授权启动的进程：

  

# kill -9 1441

  5、正常启动 mariadb：

  

# systemctl start mariadb

最后修改：2024 年 07 月 28 日
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