mysql无法启动
<h3>MYSQL服务无法启动</h3>
<pre><code class="language-shell">$-sudo service mysql start
$-Failed to start mysql.service: Unit mysql.service not found.</code></pre>
<h4>卸载当前已安装的mysql</h4>
<p>1.查看安装的mysql包</p>
<pre><code class="language-shell">$-rpm -qa|grep -i mysql//查找
mysql-8.0.26-1.1.al8.x86_64
mysql-common-8.0.26-1.1.al8.x86_64
$-rmp -ev [包名] //卸载包</code></pre>
<p>2.查找目录并删除</p>
<pre><code class="language-shell">$-find / -name mysql
/var/lib/selinux/targeted/active/modules/100/mysql
/usr/share/bash-completion/completions/mysql
/usr/share/selinux/targeted/default/active/modules/100/mysql
$-rm -rf [目录名] //删除对应的目录
$-rm -rf /etc/my.cnf //手动删除my.cnf</code></pre>
<h4>安装mysql</h4>
<p>1.<a href="https://dev.mysql.com/downloads/">https://dev.mysql.com/downloads/</a> mysql官网 选择 mysql yum repository
<img src="https://www.showdoc.com.cn/server/api/attachment/visitFile?sign=e6b0cf8bda23f3cbe49b06b9196e67a9&file=file.png" alt="" /></p>
<p>选择适合自己的版本进行download
<img src="https://www.showdoc.com.cn/server/api/attachment/visitFile?sign=7fb70445462aff59eb7492141146b575&file=file.png" alt="" />
右键复制rpm包的链接地址</p>
<p>2.下载rpm包 </p>
<pre><code class="language-shell">进入存储包的文件夹
$-wget https://dev.mysql.com/get/mysql80-community-release-el8-4.noarch.rpm
$-rpm -Uvh mysql80-community-release-el8-4.noarch.rpm //安装yum存储库
此模块会屏蔽 MySQL存储库提供的包，禁用后MySQL存储库包则可见，如果不禁用直接安装mysql则会报错：找不到安装包
$-yum -y module disable mysql
$-yum -y install mysql-community-server //安装server
$-systemctl start mysqld //启动服务
$-systemctl status mysqld //查看服务状态</code></pre>
<p>3.处理刚安装的mysql</p>
<ul>
<li>查看临时密码
cat /var/log/mysqld.log | grep password
mysql -u root -p //登录mysql</li>
<li>修改临时密码
alter user 'root'@'localhost' identified by '你的密码';</li>
<li>设置简单密码（mysql默认密码强度过高 可不设置）
set global validate_password.policy=LOW; //LOW:只验证密码的长度
set global validate_password.length=7; 设置密码长度为7</li>
</ul>
<p>远程连接数据库</p>
<ul>
<li>查看访问权限
select user,host from mysql.user;
将root用户的host改为% 允许任意主机访问</li>
<li>刷新配置
flush privileges;
最后记得开放3306端口</li>
</ul>