卸载：
- 卸载 mysql
brew uninstall mysql
- 清理缓存
brew cleanup --prune=all mysql
3）删除数据目录
rm -rf /usr/local/var/mysql
安装：
1）安装 mysql
brew install mysql
2）启动 mysql
brew services restart mysql
3）设置 mysql以及密码
./mysql_secure_installation
以下为交互模式
Securing the MySQL server deployment.
Connecting to MySQL using a blank password.
VALIDATE PASSWORD COMPONENT can be used to test passwords
and improve security. It checks the strength of password
and allows the users to set only those passwords which are
secure enough. Would you like to setup VALIDATE PASSWORD component?
Press y|Y for Yes, any other key for No: (是否设置密码强度策略，否，直接回车)
Please set the password for root here.
New password: (输入密码)
Re-enter new password: (确认密码)
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? (Press y|Y for Yes, any other key for No) : (是否使用匿名用户，否，直接回车)
... skipping.
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? (Press y|Y for Yes, any other key for No) : (是否允许远程连接，否，直接回车)
... 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? (Press y|Y for Yes, any other key for No) : (是否删除测试数据库，否，直接回车)
... skipping.
Reloading the privilege tables will ensure that all changes
made so far will take effect immediately.
Reload privilege tables now? (Press y|Y for Yes, any other key for No) : （是否重新加载权限表，是，输入）y