1、首先是想到用pip来安装pymysql
pip install mysql
报错：
cryptography requires setuptools 18.5 or newer, please upgrade to a
2、我想到的是更新pip
sudo pip install --upgrade pip
其实需要更新的是setuptools:
sudo pip install -t /usr/local/lib/python3.6/site-packages/ setuptools
3、使用pip将pymysql安装到想要的地方，针对多python版本的情况：
安装到python2.7:
sudo pip install pymysql
安装到python3.4:
sudo pip install -t /usr/local/lib/python3.4/site-packages/ pymysql
安装到python3.6:
sudo pip install -t /usr/local/lib/python3.6/site-packages/ pymysql
安装到虚拟环境中：
sudo pip install -t ~/Pycharm/py36env/lib/python3.6/site-packages pymysql
报错：
Could not fetch URL https://pypi.python.org/simple/requests/: There was a problem confirming the ssl certificate: Can't connect to HTTPS URL because the SSL module is not available. - skipping
解决方式：
sudo pip --trusted-host pypi.python.org install -t ~/PycharmProjects/py36env/lib/python3.6/site-packages/ mysql
问题解决。
