mysql无法使用命令行：
mysql：sudo ln -s /usr/local/mysql/bin/mysql /usr/local/bin
安装mysql-connector：
pip3 search mysql-connector | grep --color mysql-connector-python
mysql-connector-python-rf (2.2.2) - MySQL driver written in Python
mysql-connector-python (2.0.4) - MySQL driver written in Python
或者：
pip3 install --egg mysql-connector-python-rf==2.2.2
