Linux下安装配置MySQL5.7

查看有没有安装mariadb
```
rpm -qa | grep mariadb
```
有的话卸载 --nodeps是强制卸载不加可能会导致依赖检测失败
```
rpm -e --nodeps mariadb-libs-5.5.64-1.el7.x86_64
```
删除mariadb配置文件
```
rm -rf /etc/my.cnf*
```

下载MySQL源安装包

sudo wget http://dev.mysql.com/get/mysql57-community-release-el7-8.noarch.rpm

安装MySQL源

sudo yum localinstall mysql57-community-release-el7-8.noarch.rpm

检查MySQL源是否安装成功

sudo yum repolist enabled | grep "mysql.*-community.*"

安装MySQL

sudo yum install mysql-community-server

启动MySQL服务
```
sudo systemctl start mysqld
```

查看MySQL的启动状态

sudo systemctl status mysqld
#或者
sudo ps -le | grep mysqld

设置开机启动

sudo systemctl enable mysqld
sudo systemctl daemon-reload

修改 MySQL 中 root 本地登录密码

sudo grep 'temporary password' /var/log/mysqld.log
#如果没有grep出来 执行下面的操作
    #删除原来安装过的mysql残留的数据（这一步非常重要，问题就出在这）
    rm -rf /var/lib/mysql
    #重启mysqld服务 之后就会有了
    systemctl restart mysqld

登录MySQL，使用刚才找到的密码
```
mysql -u root -p
```

修改root用户密码（二选一）

ALTER USER 'root'@'localhost' IDENTIFIED BY 'MyNewPass4!';
set password for 'root'@'localhost'=password('MyNewPass4!');

修改密码策略修改完就可以改成简单密码了设置安全级别为LOW 密码长度为6
```
set global validate_password_policy=LOW;
set global validate_password_length=6;
```
注意：mysql5.7默认安装了密码安全检查插件（validate_password），默认密码检查策略要求密码必须包含：大小写字母、数字和特殊符号，并且长度不能少于8位。否则会提示ERROR 1819 (HY000): Your password does not satisfy the current policy requirements错误，如下图所示：

通过msyql环境变量可以查看密码策略的相关信息
```
show variables like '%password%';
```

设置远程登录

#MySQL默认只允许root帐户在本地登录，想要远程连接MySQL，必须开启root用户允许远程连接，或者添加一个允许远程连接的帐户

#开启root用户远程连接（任意IP都可以访问）
GRANT ALL PRIVILEGES ON *.* TO 'root'@'%' IDENTIFIED BY 'root用户的密码' WITH GRANT OPTION;
#开启root用户远程连接（指定192.168.110.120访问）
GRANT ALL PRIVILEGES ON *.* TO 'root'@'192.168.110.120' IDENTIFIED BY 'root用户的密码' WITH GRANT OPTION;
#安全起见， 创建远程访问用户
GRANT ALL PRIVILEGES ON *.* TO 'dadeity'@'%' IDENTIFIED BY 'daDeity@163.com' WITH GRANT OPTION;
#刷新MySQL的系统权限相关表，否则会出现拒绝访问
flush privileges;

MySQL设置

#设置MySQL默认编码为utf8
#修改 /etc/my.cnf配置文件 在[mysqld]下添加
character_set_server=utf8
init_connect='SET NAMES utf8'
#重启MySQL服务
systemctl restart mysqld
#查看MySQL默认编码如下
mysql> 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/ |
+--------------------------+----------------------------+
8 rows in set (0.01 sec)

#默认配置文件路径
配置文件：    /etc/my.cnf
日志文件：    /var/log//var/log/mysqld.log
服务启动脚本： /usr/lib/systemd/system/mysqld.service
socket文件：  /var/run/mysqld/mysqld.pid

#查看MySQL版本
mysql> SHOW VARIABLES WHERE Variable_name = 'version';
+---------------+--------+
| Variable_name | Value  |
+---------------+--------+
| version       | 5.7.29 |
+---------------+--------+

MySQL忘记root用户密码，解决方案

#在 /etc/my.cnf文件[mysqld]下面加如下命令
skip-grant-tables
#指定登录 不要密码
mysql  -u root
#修改密码 
update mysql.user set authentication_string=password('newPass') where user='root' and Host = 'localhost';
#刷新权限
flush privileges;




GRANT ALL PRIVILEGES ON *.* TO 'bewinner'@'10.25.60.120' IDENTIFIED BY 'BeWinner2020#@!' WITH GRANT OPTION;

GRANT ALL PRIVILEGES ON *.* TO 'bewinner_remote'@'114.251.40.124' IDENTIFIED BY 'BeWinner!!.' WITH GRANT OPTION;