参考：（使用Homebrew安装MySQL https://www.cnblogs.com/lidyan/p/6587718.html）
安装命令：
brew install mysql
安装完成之后，启动mysql：
mysql.server start
发现无此命令：
command not found
首先，检查是否是安装了。重新执行一遍：
brew install mysql
提示：
Warning: mysql 8.0.11 is already installed, it's just not linked
You can use `brew link mysql` to link this version.
然后网上查找解决方法，执行：
brew link mysql
报错：
Linking /usr/local/Cellar/mysql/8.0.11...
Error: Could not symlink .
/usr/local/opt is not writable.
查找解决方法，以下语句执行成功：
先到local目录：sudo mkdir opt
再回到～目录：sudo chown -R `whoami`:admin /usr/local/opt
解决了问题后，重新执行：
brew link mysql
提示：
Linking /usr/local/Cellar/mysql/8.0.11... 79 symlinks created
重新执行:
mysql.server start
登录mysql：
mysql -uroot
报错：
dyld: Library not loaded: /usr/local/opt/openssl/lib/libssl.1.0.0.dylib
Referenced from: /usr/local/bin/mysql
Reason: image not found
或启动CMS后台python main.py runwebapp时，报错：
mportError: dlopen(/Library/Python/2.7/site-packages/_mysql.so, 2): Library not loaded: /usr/local/opt/openssl/lib/libssl.1.0.0.dylib
Referenced from: /usr/local/opt/mysql/lib/libmysqlclient.20.dylib
Reason: image not found
解决：参考（Mac openssl未找到/加载失败问题处理 https://www.jianshu.com/p/c6d6a60002e4）
brew remove openssl
brew uninstall --force openssl
brew install openssl
再次登录：
mysql -uroot
成功！
补充：
问题：Library not loaded libmysqlclient.20.dylib image not found
libmysqlclient.20.dylib brew安装的最新是 libmysqlclient.21.dylib
解决方法：
到该目录查看(/usr/local/opt/mysql/lib/)：ls -l libmysqlclient.21.dylib
先备份，命令： sudo cp libmysqlclient.21.dylib libmysqlclient.21.dylib.backup
再映射地址，命令：sudo ln -s /usr/local/opt/mysql/lib/libmysqlclient.21.dylib /usr/local/opt/mysql/lib/libmysqlclient.20.dylib
查看映射情况：ls -l libmysqlclient.21.dylib