这里介绍一下为什么会用数据库，主要做什么用
一、卸载Mariadb
从 CentOS 7 系统开始，MariaDB 成为 yum 源中默认的数据库安装包。在 CentOS 7 及以上的系统中使用 yum 安装 MySQL 包将无法使用 MySQL。您可以选择使用完全兼容的 MariaDB，或依照本文介绍配置来继续使用 MySQL。
查看安装了mariadb相关的模块
[root@localhost ~]# rpm -qa | grep mariadb
mariadb-libs-5.5.44-2.el7.centos.x86_64
然后进行卸载
[root@localhost ~]# rpm -e mariadb-libs-5.5.44-2.el7.centos.x86_64
error: Failed dependencies:
libmysqlclient.so.18()(64bit) is needed by (installed) postfix-2:2.10.1-6.el7.x86_64
libmysqlclient.so.18(libmysqlclient_18)(64bit) is needed by (installed) postfix-2:2.10.1-6.el7.x86_64
会提示有依赖于这的安装包，那么就强制卸载，不查检依赖：
[root@localhost ~]# rpm -e --nodeps mariadb-libs-5.5.44-2.el7.centos.x86_64
将所有的mariadb安装包都删除，然后再次键入 rpm -qa | grep mariadb 查看是否卸载成功
二、卸载MySQL
为了防止重装，建议先卸载，可以操作以下命令
查看yum是否安装过mysql
yum list installed mysql*
查看mysql安装了哪些东西
rpm -qa | grep -i mysql
开始卸载，（这里只列两条，应该是卸载上面查询出来的结果！！）
yum remove mysql-community-common-5.7.20-1.el7.x86_64
yum remove mysql-community-client-5.7.20-1.el7.x86_64
查看是否卸载完成
[root@localhost ~]# rpm -qa | grep -i mysql
[root@localhost ~]#
查找mysql相关目录
[root@localhost ~]# find / -name mysql
/etc/selinux/targeted/active/modules/100/mysql
删除mysql相关目录（后面的地址，替换成查询返回的地址，有多条，顺序执行 rm -rf /*/*/*操作 ）
[root@localhost ~]# rm -rf /etc/selinux/targeted/active/modules/100/mysql
[root@localhost ~]#
删除/etc/my.cnf
[root@localhost ~]# rm -rf /etc/my.cnf
删除/var/log/mysqld.log（如果不删除这个文件，会导致新安装的mysql无法生存新密码，导致无法登录）
[root@localhost ~]# rm -rf /var/log/mysqld.log
三、安装MySQL
大家都知道，centos自带的repo是不会自动更新每个软件的最新版本，所以无法通过yum方式安装MySQL的高级版本。所以，即使我使劲用yum -y install mysql
mysql-server mysql-devel，也是没有人会鸟我的。
所以，正确的安装mysql5姿势是要先安装带有可用的mysql5系列社区版资源的rpm包
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rpm -Uvh http://dev.mysql.com/get/mysql-community-release-el7-5.noarch.rpm先安装带有可用mysql5系列社区版资源的rpm包
[root@localhost ~]# rpm -Uvh http://dev.mysql.com/get/mysql-community-release-el7-5.noarch.rpm
Retrieving http://dev.mysql.com/get/mysql-community-release-el7-5.noarch.rpm
Preparing... ################################# [100%]
Updating / installing...
1:mysql-community-release-el7-5 ################################# [100%]
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yum repolist enabled | grep "mysql.*-community.*"查看当前可用的mysql安装资源
[root@localhost ~]# yum repolist enabled | grep "mysql.*-community.*"
mysql-connectors-community/x86_64 MySQL Connectors Community 65
mysql-tools-community/x86_64 MySQL Tools Community 69
mysql56-community/x86_64 MySQL 5.6 Community Server 412
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yum -y install mysql-community-server使用yum的方式安装MySQL，一般来说，只要安装mysql-server和mysql-client
[root@localhost ~]# yum -y install mysql-community-server
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
Resolving Dependencies
--> Running transaction check
---> Package mysql-community-server.x86_64 0:5.6.41-2.el7 will be installed
--> Processing Dependency: mysql-community-common(x86-64) = 5.6.41-2.el7 for package: mysql-community-server-5.6.41-2.el7.x86_64
--> Processing Dependency: mysql-community-client(x86-64) >= 5.6.10 for package: mysql-community-server-5.6.41-2.el7.x86_64
--> Processing Dependency: perl(Data::Dumper) for package: mysql-community-server-5.6.41-2.el7.x86_64
--> Processing Dependency: perl(DBI) for package: mysql-community-server-5.6.41-2.el7.x86_64
--> Running transaction check
---> Package mysql-community-client.x86_64 0:5.6.41-2.el7 will be installed
--> Processing Dependency: mysql-community-libs(x86-64) >= 5.6.10 for package: mysql-community-client-5.6.41-2.el7.x86_64
---> Package mysql-community-common.x86_64 0:5.6.41-2.el7 will be installed
---> Package perl-DBI.x86_64 0:1.627-4.el7 will be installed
--> Processing Dependency: perl(RPC::PlServer) >= 0.2001 for package: perl-DBI-1.627-4.el7.x86_64
--> Processing Dependency: perl(RPC::PlClient) >= 0.2000 for package: perl-DBI-1.627-4.el7.x86_64
---> Package perl-Data-Dumper.x86_64 0:2.145-3.el7 will be installed
--> Running transaction check
---> Package mysql-community-libs.x86_64 0:5.6.41-2.el7 will be installed
---> Package perl-PlRPC.noarch 0:0.2020-14.el7 will be installed
--> Processing Dependency: perl(Net::Daemon) >= 0.13 for package: perl-PlRPC-0.2020-14.el7.noarch
--> Processing Dependency: perl(Net::Daemon::Test) for package: perl-PlRPC-0.2020-14.el7.noarch
--> Processing Dependency: perl(Net::Daemon::Log) for package: perl-PlRPC-0.2020-14.el7.noarch
--> Processing Dependency: perl(Compress::Zlib) for package: perl-PlRPC-0.2020-14.el7.noarch
--> Running transaction check
---> Package perl-IO-Compress.noarch 0:2.061-2.el7 will be installed
--> Processing Dependency: perl(Compress::Raw::Zlib) >= 2.061 for package: perl-IO-Compress-2.061-2.el7.noarch
--> Processing Dependency: perl(Compress::Raw::Bzip2) >= 2.061 for package: perl-IO-Compress-2.061-2.el7.noarch
---> Package perl-Net-Daemon.noarch 0:0.48-5.el7 will be installed
--> Running transaction check
---> Package perl-Compress-Raw-Bzip2.x86_64 0:2.061-3.el7 will be installed
---> Package perl-Compress-Raw-Zlib.x86_64 1:2.061-4.el7 will be installed
--> Finished Dependency Resolution
Dependencies Resolved
========================================================================================================================
Package Arch Version Repository Size
========================================================================================================================
Installing:
mysql-community-server x86_64 5.6.41-2.el7 mysql56-community 59 M
Installing for dependencies:
mysql-community-client x86_64 5.6.41-2.el7 mysql56-community 19 M
mysql-community-common x86_64 5.6.41-2.el7 mysql56-community 257 k
mysql-community-libs x86_64 5.6.41-2.el7 mysql56-community 2.0 M
perl-Compress-Raw-Bzip2 x86_64 2.061-3.el7 base 32 k
perl-Compress-Raw-Zlib x86_64 1:2.061-4.el7 base 57 k
perl-DBI x86_64 1.627-4.el7 base 802 k
perl-Data-Dumper x86_64 2.145-3.el7 base 47 k
perl-IO-Compress noarch 2.061-2.el7 base 260 k
perl-Net-Daemon noarch 0.48-5.el7 base 51 k
perl-PlRPC noarch 0.2020-14.el7 base 36 k
Transaction Summary
========================================================================================================================
Install 1 Package (+10 Dependent packages)
Total download size: 82 M
Installed size: 354 M
Downloading packages:
warning: /var/cache/yum/x86_64/7/mysql56-community/packages/mysql-community-common-5.6.41-2.el7.x86_64.rpm: Header V3 DSA/SHA1 Signature, key ID 5072e1f5: NOKEY
Public key for mysql-community-common-5.6.41-2.el7.x86_64.rpm is not installed
(1/11): mysql-community-common-5.6.41-2.el7.x86_64.rpm | 257 kB 00:00:00
(2/11): mysql-community-libs-5.6.41-2.el7.x86_64.rpm | 2.0 MB 00:00:00
(3/11): perl-Compress-Raw-Bzip2-2.061-3.el7.x86_64.rpm | 32 kB 00:00:00
(4/11): perl-Compress-Raw-Zlib-2.061-4.el7.x86_64.rpm | 57 kB 00:00:00
(5/11): perl-Data-Dumper-2.145-3.el7.x86_64.rpm | 47 kB 00:00:00
(6/11): perl-IO-Compress-2.061-2.el7.noarch.rpm | 260 kB 00:00:00
(7/11): perl-Net-Daemon-0.48-5.el7.noarch.rpm | 51 kB 00:00:00
(8/11): perl-PlRPC-0.2020-14.el7.noarch.rpm | 36 kB 00:00:00
(9/11): perl-DBI-1.627-4.el7.x86_64.rpm | 802 kB 00:00:00
(10/11): mysql-community-client-5.6.41-2.el7.x86_64.rpm | 19 MB 00:00:01
(11/11): mysql-community-server-5.6.41-2.el7.x86_64.rpm | 59 MB 00:00:03
------------------------------------------------------------------------------------------------------------------------
Total 17 MB/s | 82 MB 00:00:04
Retrieving key from file:/etc/pki/rpm-gpg/RPM-GPG-KEY-mysql
Importing GPG key 0x5072E1F5:
Userid : "MySQL Release Engineering <mysql-build@oss.oracle.com>"
Fingerprint: a4a9 4068 76fc bd3c 4567 70c8 8c71 8d3b 5072 e1f5
Package : mysql-community-release-el7-5.noarch (installed)
From : file:/etc/pki/rpm-gpg/RPM-GPG-KEY-mysql
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
Warning: RPMDB altered outside of yum.
** Found 2 pre-existing rpmdb problem(s), 'yum check' output follows:
2:postfix-2.10.1-6.el7.x86_64 has missing requires of libmysqlclient.so.18()(64bit)
2:postfix-2.10.1-6.el7.x86_64 has missing requires of libmysqlclient.so.18(libmysqlclient_18)(64bit)
Installing : mysql-community-common-5.6.41-2.el7.x86_64 1/11
Installing : perl-Data-Dumper-2.145-3.el7.x86_64 2/11
Installing : mysql-community-libs-5.6.41-2.el7.x86_64 3/11
Installing : mysql-community-client-5.6.41-2.el7.x86_64 4/11
Installing : perl-Compress-Raw-Bzip2-2.061-3.el7.x86_64 5/11
Installing : perl-Net-Daemon-0.48-5.el7.noarch 6/11
Installing : 1:perl-Compress-Raw-Zlib-2.061-4.el7.x86_64 7/11
Installing : perl-IO-Compress-2.061-2.el7.noarch 8/11
Installing : perl-PlRPC-0.2020-14.el7.noarch 9/11
Installing : perl-DBI-1.627-4.el7.x86_64 10/11
Installing : mysql-community-server-5.6.41-2.el7.x86_64 11/11
Verifying : mysql-community-server-5.6.41-2.el7.x86_64 1/11
Verifying : mysql-community-client-5.6.41-2.el7.x86_64 2/11
Verifying : mysql-community-libs-5.6.41-2.el7.x86_64 3/11
Verifying : perl-Data-Dumper-2.145-3.el7.x86_64 4/11
Verifying : mysql-community-common-5.6.41-2.el7.x86_64 5/11
Verifying : perl-IO-Compress-2.061-2.el7.noarch 6/11
Verifying : 1:perl-Compress-Raw-Zlib-2.061-4.el7.x86_64 7/11
Verifying : perl-Net-Daemon-0.48-5.el7.noarch 8/11
Verifying : perl-DBI-1.627-4.el7.x86_64 9/11
Verifying : perl-Compress-Raw-Bzip2-2.061-3.el7.x86_64 10/11
Verifying : perl-PlRPC-0.2020-14.el7.noarch 11/11
Installed:
mysql-community-server.x86_64 0:5.6.41-2.el7
Dependency Installed:
mysql-community-client.x86_64 0:5.6.41-2.el7 mysql-community-common.x86_64 0:5.6.41-2.el7
mysql-community-libs.x86_64 0:5.6.41-2.el7 perl-Compress-Raw-Bzip2.x86_64 0:2.061-3.el7
perl-Compress-Raw-Zlib.x86_64 1:2.061-4.el7 perl-DBI.x86_64 0:1.627-4.el7
perl-Data-Dumper.x86_64 0:2.145-3.el7 perl-IO-Compress.noarch 0:2.061-2.el7
perl-Net-Daemon.noarch 0:0.48-5.el7 perl-PlRPC.noarch 0:0.2020-14.el7
Complete!
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yum list installed mysql*查看是否安装mysql，检查是否安装完成
root@localhost ~]# yum list installed mysql*
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
Installed Packages
mysql-community-client.x86_64 5.6.41-2.el7 @mysql56-communitymysql-community-common.x86_64 5.6.41-2.el7 @mysql56-communitymysql-community-libs.x86_64 5.6.41-2.el7 @mysql56-communitymysql-community-release.noarch el7-5 installed
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systemctl enable mysqld加入开机启动
[root@localhost ~]# systemctl enable mysqld
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systemctl start mysqld启动mysql服务进程
[root@localhost ~]# systemctl start mysqld
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systemctl list-unit-files验证是否加入开机启动列表中
[root@localhost ~]# systemctl list-unit-files
...
...
mysql.service enabled
mysqld.service enabled
...
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ps -ef | grep mysql查看mysql安装路径
[root@localhost ~]# ps -ef | grep mysql
mysql 24362 1 0 11:33 ? 00:00:00 /bin/sh /usr/bin/mysqld_safe --basedir=/usr
mysql 24529 24362 0 11:33 ? 00:00:00 /usr/sbin/mysqld --basedir=/usr --datadir=/var/lib/mysql --plugin-dir=/usr/lib64/mysql/plugin --log-error=/var/log/mysqld.log --pid-file=/var/run/mysqld/mysqld.pid --socket=/var/lib/mysql/mysql.sock
root 24576 23955 0 11:50 pts/0 00:00:00 grep --color=auto mysql
查询文件运行所在地址，直接用下面的命令
[root@localhost ~]# which mysql
/usr/bin/mysql
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mysql_secure_installation重置密码
[root@localhost ~]# mysql_secure_installation [设置root密码]
NOTE: RUNNING ALL PARTS OF THIS SCRIPT IS RECOMMENDED FOR ALL MySQL
SERVERS IN PRODUCTION USE! PLEASE READ EACH STEP CAREFULLY!
In order to log into MySQL to secure it, we'll need the current
password for the root user. If you've just installed MySQL, 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 MySQL
root user without the proper authorisation.
Set root password? [Y/n] y [是否设置root密码]
New password:
Re-enter new password:
Password updated successfully!
Reloading privilege tables..
... Success!
By default, a MySQL installation has an anonymous user, allowing anyone
to log into MySQL 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 [删除匿名用户]
... 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] n [禁止root远程登录]
... skipping.
By default, MySQL 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 [删除test数据库]
- Dropping test database...
ERROR 1008 (HY000) at line 1: Can't drop database 'test'; database doesn't exist
... Failed! Not critical, keep moving...
- 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 [刷新权限]
... Success!
All done! If you've completed all of the above steps, your MySQL
installation should now be secure.
Thanks for using MySQL!
Cleaning up...
-
mysql -V查看mysql安装版本号
[root@localhost ~]# mysql -V
mysql Ver 14.14 Distrib 5.6.41, for Linux (x86_64) using EditLine wrapper
