windowsでpip installを使うにはpip の前に「py -m 」を付けます。
例)
py -m pip install pandas as pd
py -m pip install openpyxl
py -m pip install requests
py -m pip install bs4
py -m pip install lxml
py -m pip install selenium
py -m pip install mysql-connector-python
py -m pip install sshtunnel
py -m pip install urllib
py -m pip install mysqlclient