Hey @Utsav_Tripathi,
I’m sorry, I got thrown off by the error! 
You’re looking to actually update your sales database with new entries and save that correct? Silly me! You can do that and we actually have created tutorials on exactly this, and how to connect to different common databases! The way you have set it up works locally but not once your app is deployed.
Actually, you can find in our Documentation the links on how to connect to a database of your choice 
https://docs.streamlit.io/en/stable/tutorial/databases.html
This will make your app work and should eliminate that permission denied error! You can even connect to a public or private google sheet (which could be a simple and fast way to get your app working as you intended!) 
Happy Streamlit-ing!
Marisa