ERROR: Could not find a version that satisfies the requirement pymysql (from versions: none) ERROR:

pip安装pymysql存储库错误：

pip3 install pymysql
Collecting pymysql
  WARNING: Retrying (Retry(total=4, connect=None, read=None, redirect=None, status=None)) after connection broken by 'ConnectTimeoutError(, 'Connection to pypi.org timed out. (connect timeout=15)')': /simple/pymysql/
  WARNING: Retrying (Retry(total=3, connect=None, read=None, redirect=None, status=None)) after connection broken by 'ConnectTimeoutError(, 'Connection to pypi.org timed out. (connect timeout=15)')': /simple/pymysql/
  WARNING: Retrying (Retry(total=2, connect=None, read=None, redirect=None, status=None)) after connection broken by 'ConnectTimeoutError(, 'Connection to pypi.org timed out. (connect timeout=15)')': /simple/pymysql/
  WARNING: Retrying (Retry(total=1, connect=None, read=None, redirect=None, status=None)) after connection broken by 'ConnectTimeoutError(, 'Connection to pypi.org timed out. (connect timeout=15)')': /simple/pymysql/
  WARNING: Retrying (Retry(total=0, connect=None, read=None, redirect=None, status=None)) after connection broken by 'ConnectTimeoutError(, 'Connection to pypi.org timed out. (connect timeout=15)')': /simple/pymysql/
  ERROR: Could not find a version that satisfies the requirement pymysql (from versions: none)
ERROR: No matching distribution found for pymysql

使用pip安装其他模块时也可能出现上述错误，主要原因是网络的问题，需要使用国内的镜像源来加速，比如豆瓣源

因此命令可以使用：

pip install pymysql -i http://pypi.douban.com/simple/ --trusted-host pypi.douban.com