安装MySQL5.7

1.下载

打开官网下载页面: https://downloads.mysql.com/archives/community/，在这里我选择5.7.28版本，Operating System一栏通常没有CentOS，选择RedHat即可，OS Version选择7，X86_64，然后下载第一个mysql-5.7.28-1.el7.x86_64.rpm-bundle.tar

下载完成后，将文件移动到/opt下，并解压，会解压出多个rpm软件包

[root@localhost opt]# tar -xvf mysql-5.7.28-1.el7.x86_64.rpm-bundle.tar 
mysql-community-embedded-5.7.28-1.el7.x86_64.rpm
mysql-community-libs-compat-5.7.28-1.el7.x86_64.rpm
mysql-community-devel-5.7.28-1.el7.x86_64.rpm
mysql-community-embedded-compat-5.7.28-1.el7.x86_64.rpm
mysql-community-libs-5.7.28-1.el7.x86_64.rpm
mysql-community-test-5.7.28-1.el7.x86_64.rpm
mysql-community-common-5.7.28-1.el7.x86_64.rpm
mysql-community-embedded-devel-5.7.28-1.el7.x86_64.rpm
mysql-community-client-5.7.28-1.el7.x86_64.rpm
mysql-community-server-5.7.28-1.el7.x86_64.rpm

2.安装前准备

2.1 卸载自带的mariadb

安装基于CentOS 7.9.2009

[root@localhost ~]# cat /etc/redhat-release 
CentOS Linux release 7.9.2009 (Core)

CentOS 7.9系统预装了一个mariadb数据库，这个数据库是MySQL的”姐妹”，都是同一个作者编写的，mariadb会在/etc目录生成一个my.cnf作为配置文件，MySQL安装后也会在/etc目录生成一个my.cnf，因此为了排除干扰，首先要把预装的mariadb卸载掉。

查看是否预装：

[root@localhost ~]# rpm -qa | grep -i maria
mariadb-libs-5.5.68-1.el7.x86_64

[root@localhost ~]# ls /etc/ | grep my
my.cnf
my.cnf.d

卸载mariadb

rpm -e --nodeps mariadb-libs

2.2 安装依赖

截至目前，CentOS7的yum源已经无法访问，因此需要先更换为阿里巴巴的yum源

cp /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup

curl -o /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo

yum clean all

yum makecache

然后安装依赖项，我采用的系统版本需要额外安装这两个依赖，缺失这两个将导致后续安装mysql-community-server时出错

yum install -y net-tools

yum install -y perl

3.安装和初始化

cd进入/opt目录安装刚刚解压出的软件包，不需要每个都安装，仅安装MySQL的Server和Client以及依赖的包，安装需要按照顺序，因为rpm包有相互的依赖关系，需要安装的包以及安装顺序如下：

1. mysql-community-common-5.7.28-1.el7.x86_64.rpm
2. mysql-community-libs-5.7.28-1.el7.x86_64.rpm
3. mysql-community-client-5.7.28-1.el7.x86_64.rpm
4. mysql-community-server-5.7.28-1.el7.x86_64.rpm

使用rpm -ivh命令安装这些包

[root@localhost opt]# rpm -ivh mysql-community-common-5.7.28-1.el7.x86_64.rpm
警告：mysql-community-common-5.7.28-1.el7.x86_64.rpm: 头V3 DSA/SHA1 Signature, 密钥 ID 5072e1f5: NOKEY
准备中...                          ################################# [100%]
正在升级/安装...
   1:mysql-community-common-5.7.28-1.e################################# [100%]
[root@localhost opt]# rpm -ivh mysql-community-libs-
mysql-community-libs-5.7.28-1.el7.x86_64.rpm         mysql-community-libs-compat-5.7.28-1.el7.x86_64.rpm
[root@localhost opt]# rpm -ivh  mysql-community-libs-5.7.28-1.el7.x86_64.rpm
警告：mysql-community-libs-5.7.28-1.el7.x86_64.rpm: 头V3 DSA/SHA1 Signature, 密钥 ID 5072e1f5: NOKEY
准备中...                          ################################# [100%]
正在升级/安装...
   1:mysql-community-libs-5.7.28-1.el7################################# [100%]
[root@localhost opt]# rpm -ivh  mysql-community-client-5.7.28-1.el7.x86_64.rpm
警告：mysql-community-client-5.7.28-1.el7.x86_64.rpm: 头V3 DSA/SHA1 Signature, 密钥 ID 5072e1f5: NOKEY
准备中...                          ################################# [100%]
正在升级/安装...
   1:mysql-community-client-5.7.28-1.e################################# [100%]
[root@localhost opt]# rpm -ivh  mysql-community-server-5.7.28-1.el7.x86_64.rpm
警告：mysql-community-server-5.7.28-1.el7.x86_64.rpm: 头V3 DSA/SHA1 Signature, 密钥 ID 5072e1f5: NOKEY
准备中...                          ################################# [100%]
正在升级/安装...
   1:mysql-community-server-5.7.28-1.e################################# [100%]

通过rpm -qa已经能看到装上去的包了

[root@localhost opt]# rpm -qa | grep mysql
mysql-community-libs-5.7.28-1.el7.x86_64
mysql-community-common-5.7.28-1.el7.x86_64
mysql-community-client-5.7.28-1.el7.x86_64
mysql-community-server-5.7.28-1.el7.x86_64

查看一下安装的版本

[root@localhost opt]# mysql --version
mysql  Ver 14.14 Distrib 5.7.28, for Linux (x86_64) using  EditLine wrapper

为了保证数据库目录与文件的所有者为mysql登录用户，如果是以root身份运行mysql服务，需要执行下面的命令初始化:

mysqld --initialize --user=mysql

说明: --initialize选项默认以安全模式来初始化，则会为root用户生成一个密码并将该密码标记为过期，登录后你需要设置一个新的密码。生成的临时密码会往日志中记录一份，查看密码:

cat /var/log/mysqld.log

[root@localhost opt]# mysqld --initialize --user=mysql
[root@localhost opt]# cat /var/log/mysqld.log
2025-04-06T12:26:08.004754Z 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details).
2025-04-06T12:26:08.339163Z 0 [Warning] InnoDB: New log files created, LSN=45790
2025-04-06T12:26:08.403698Z 0 [Warning] InnoDB: Creating foreign key constraint system tables.
2025-04-06T12:26:08.470936Z 0 [Warning] No existing UUID has been found, so we assume that this is the first time that this server has been started. Generating a new UUID: 5151ca04-12e2-11f0-8409-000c29920d74.
2025-04-06T12:26:08.472919Z 0 [Warning] Gtid table is not ready to be used. Table 'mysql.gtid_executed' cannot be opened.
2025-04-06T12:26:10.249602Z 0 [Warning] CA certificate ca.pem is self signed.
2025-04-06T12:26:10.762512Z 1 [Note] A temporary password is generated for root@localhost: G*kRrqwYn7KX

接下来启动服务

systemctl start mysqld

[root@localhost opt]# systemctl status mysqld
● mysqld.service - MySQL Server
   Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled; vendor preset: disabled)
   Active: active (running) since 日 2025-04-06 20:27:54 CST; 8s ago
     Docs: man:mysqld(8)
           http://dev.mysql.com/doc/refman/en/using-systemd.html
  Process: 1468 ExecStart=/usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysqld.pid $MYSQLD_OPTS (code=exited, status=0/SUCCESS)
  Process: 1451 ExecStartPre=/usr/bin/mysqld_pre_systemd (code=exited, status=0/SUCCESS)
 Main PID: 1471 (mysqld)
   CGroup: /system.slice/mysqld.service
           └─1471 /usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysqld.pid

4月 06 20:27:53 localhost.localdomain systemd[1]: Starting MySQL Server...
4月 06 20:27:54 localhost.localdomain systemd[1]: Started MySQL Server.

4.登录和基础配置

4.1登录并重置密码

用之前生成的初始密码登录MySQL的root用户，命令是：mysql -uroot -p，Enter password:后输入密码回车，登录成功并进入MySQL交互命令行，但是不能操作，提示需要重置root密码

[root@localhost opt]# mysql -uroot -p
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.7.28

Copyright (c) 2000, 2019, 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;
ERROR 1820 (HY000): You must reset your password using ALTER USER statement before executing this statement.

执行这个语句重置密码

alter user 'root'@'localhost' identified by 'lzj';

4.2 打开远程连接

安装好的MySQL会自带4个数据库，连接配置的表位于mysql库的user表上，use mysql;将当前库切换为mysql，通过select host,user from user;查看得知系统中的4个用户都仅允许本机访问

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| sys                |
+--------------------+
4 rows in set (0.00 sec)

mysql> use mysql;
Database changed
mysql> select host,user from user;
+-----------+---------------+
| host      | user          |
+-----------+---------------+
| localhost | mysql.session |
| localhost | mysql.sys     |
| localhost | root          |
+-----------+---------------+
3 rows in set (0.00 sec)

通过执行以下语句修改root用户可访问的地址，可以采用通配符，按自己需要修改即可，我选择直接修改为%

允许root用户从192.168.1.x主机访问

update mysql.user set host ='192.168.1.%' where user = 'root';

允许root用户从一切远程主机访问

update mysql.user set host ='%' where user = 'root';

修改完成，刷新权限，即可远程连接

flush privileges;

远程连接前一定要关闭CentOS7自带的防火墙firewalld

4.3 修改字符集

在MySQL8.0版本之前，默认字符集为latin1，utf8字符集指向的是utf8mb3。网站开发人员在数据库设计的时候往往会将编码修改为utf8字符集，如果遗忘修改默认的编码，就会出现乱码的问题，从MySQL8.0开始，数据库的默认编码将改为utf8mb4，从而避免上述乱码的问题。

查看当前字符集

show variables like '%char%';

mysql> show variables like '%char%';
+--------------------------+----------------------------+
| Variable_name            | Value                      |
+--------------------------+----------------------------+
| character_set_client     | utf8                       |
| character_set_connection | utf8                       |
| character_set_database   | latin1                     |
| character_set_filesystem | binary                     |
| character_set_results    | utf8                       |
| character_set_server     | latin1                     |
| character_set_system     | utf8                       |
| character_sets_dir       | /usr/share/mysql/charsets/ |
+--------------------------+----------------------------+
8 rows in set (0.00 sec)

字符集不支持中文，因此MySQL5.7需要修改服务端字符集，修改字符集的配置文件位于/etc/my.cnf，将配置添加在[mysqld]节点上

[mysqld]

character-set-server = utf8

修改后新建的库和表才会使用utf8，之前建的库表的字符集不会被自动修改，需要手动修改：

⚠️ utf8兼容latin1，因此之前的数据支持修改字符集为utf8，如果不兼容就可能出现乱码问题，不兼容的情况可以将数据导出在重新插入

修改库

alter database db_xxx character set 'utf8';

修改表

alter table tb_xxx convert to character set 'utf8';