Linux 安装mysql

1、到mysql 的官网下载mysql 的yum包

下载并安装MySQL官方的 Yum Repository

wget -i -c  https://dev.mysql.com/get/mysql80-community-release-el7-3.noarch.rpm

使用上面的命令就直接下载了安装用的Yum Repository，大概25KB的样子，然后就可以直接yum安装了。

yum -y install mysql80-community-release-el7-3.noarch.rpm

已加载插件：fastestmirror
正在检查 mysql80-community-release-el7-3.noarch.rpm: mysql80-community-release-el7-3.noarch
mysql80-community-release-el7-3.noarch.rpm 将被安装
正在解决依赖关系
--> 正在检查事务
---> 软件包 mysql80-community-release.noarch.0.el7-3 将被 安装
--> 解决依赖关系完成

依赖关系解决

==============================================================================================================================================================
 Package                                     架构                     版本                    源                                                         大小
==============================================================================================================================================================
正在安装:
 mysql80-community-release                   noarch                   el7-3                   /mysql80-community-release-el7-3.noarch                    31 k

事务概要
==============================================================================================================================================================
安装  1 软件包

总计：31 k
安装大小：31 k
Downloading packages:
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
  正在安装    : mysql80-community-release-el7-3.noarch                                                                                                    1/1
  验证中      : mysql80-community-release-el7-3.noarch                                                                                                    1/1

已安装:
  mysql80-community-release.noarch 0:el7-3

完毕！

安装mysql 服务器

yum -y install mysql-community-server

这步可能会花些时间，安装完成后就会覆盖掉之前的mariadb。

已安装:
  mysql-community-libs.x86_64 0:8.0.20-1.el7       mysql-community-libs-compat.x86_64 0:8.0.20-1.el7       mysql-community-server.x86_64 0:8.0.20-1.el7

作为依赖被安装:
  mysql-community-client.x86_64 0:8.0.20-1.el7        mysql-community-common.x86_64 0:8.0.20-1.el7        net-tools.x86_64 0:2.0-0.25.20131004git.el7

作为依赖被升级:
  postfix.x86_64 2:2.10.1-9.el7

替代:
  mariadb-libs.x86_64 1:5.5.64-1.el7

完毕！

2 MySQL数据库设置

  首先启动MySQL

systemctl start  mysqld.service

查看MySQL状态

[ home]# systemctl start  mysqld.service
[ home]# systemctl status mysqld.service

● mysqld.service - MySQL Server
   Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled; vendor preset: disabled)
   Active: active (running) since 四 2020-04-30 08:39:23 CST; 3min 28s ago
     Docs: man:mysqld(8)
           http://dev.mysql.com/doc/refman/en/using-systemd.html
  Process: 50681 ExecStartPre=/usr/bin/mysqld_pre_systemd (code=exited, status=0/SUCCESS)
 Main PID: 50792 (mysqld)
   Status: "Server is operational"
    Tasks: 38
   Memory: 420.6M
   CGroup: /system.slice/mysqld.service
           └─50792 /usr/sbin/mysqld

4月 30 08:38:42 localhost systemd[1]: Starting MySQL Server...
4月 30 08:39:23 localhost systemd[1]: Started MySQL Server.

 此时MySQL已经开始正常运行，不过要想进入MySQL还得先找出此时root用户的密码，通过如下命令可以在日志文件中找出密码：

[ home]# grep "password" /var/log/mysqld.log
2020-04-30T00:38:58.704393Z 6 [Note] [MY-010454] [Server] A temporary password is generated for : ******

如下命令进入数据库：

[ home]# mysql -uroot -p
Enter password:
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 8
Server version: 8.0.20

Copyright (c) 2000, 2020, 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>

输入初始密码，此时不能做任何事情，因为MySQL默认必须修改密码之后才能操作数据库：

ALTER USER ‘root‘@‘localhost‘ IDENTIFIED BY ‘new password‘;

这里有个问题，新密码设置的时候如果设置的过于简单会报错：

ERROR 1819 (HY000): Your password does not satisfy the current policy requirements

原因是因为MySQL有密码设置的规范，具体是与validate_password_policy的值有关：

MySQL完整的初始密码规则可以通过如下命令查看：

mysql> SHOW VARIABLES LIKE ‘validate_password%‘;
+--------------------------------------+-------+
| Variable_name                        | Value |
+--------------------------------------+-------+
| validate_password_check_user_name    | OFF   |
| validate_password_dictionary_file    |       |
| validate_password_length             | 4     |
| validate_password_mixed_case_count   | 1     |
| validate_password_number_count       | 1     |
| validate_password_policy             | LOW   |
| validate_password_special_char_count | 1     |
+--------------------------------------+-------+
rows in set (0.01 sec)

密码的长度是由validate_password_length决定的，而validate_password_length的计算公式是：

validate_password_length = validate_password_number_count + validate_password_special_char_count + (2 * validate_password_mixed_case_count)

我的是已经修改过的，初始情况下第一个的值是ON，validate_password_length是8。可以通过如下命令修改：

mysql> set global validate_password_policy=0;
mysql> set global validate_password_length=1;

设置之后就是我上面查出来的那几个值了，此时密码就可以设置的很简单，例如1234之类的。到此数据库的密码设置就完成了。

  但此时还有一个问题，就是因为安装了Yum Repository，以后每次yum操作都会自动更新，需要把这个卸载掉：

yum -y remove mysql80-community-release-el7-3.noarch

此时才算真的完成了。

如果在密码设置那里不想改，直接将密码设置成比较复杂的密码 大写+小写+特殊字符+数字 即可

原文转自：https://www.cnblogs.com/luohanguo/p/9045391.html