WARNING: You are using pip version 19.2.3, however version 20.1 is available.

安装requests库时，输入：pip install requests，发生错误：WARNING: You are using pip version 19.2.3, however version 20.1 is available.
You should consider upgrading via the 'python -m pip install --upgrade pip' command.

 

解决方法：输入：pip3 install --index-url https://pypi.douban.com/simple requests

出现：WARNING: You are using pip version 19.2.3, however version 20.1 is available.
You should consider upgrading via the 'python -m pip install --upgrade pip' command.

再次输入：python -m pip install --upgrade pip --index-url https://pypi.douban.com/simple requests

成功安装

Installing collected packages: pip
  Found existing installation: pip 19.2.3
    Uninstalling pip-19.2.3:
      Successfully uninstalled pip-19.2.3
Successfully installed pip-20.1