This tutorial is on how to READ from a Google Sheet; if you would like to WRITE to a Google Sheet from WordPress click here: https://youtu.be/k7Il8qJcXLs
Again, if you want to save customer contact information into Google Sheets, then checkout this tutorial where I show you how to create a plugin that connects Google Sheets to Contact Form 7 https://www.youtube.com/watch?v=k7Il8qJcXLs
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Yes, you can use Google Sheets as a database!
Connecting a WordPress site with Google Sheets too isn't difficult. By using the Google Sheet API, you can have WordPress pulling data from a Google Sheet pretty quickly. In this video tutorial, learn how to use Google Sheets as a simple database for your WordPress site.
Quickly we will make a connection to a Google Sheet using their free API. Then we will retrieve the data in a way that you can manipulate using PHP.
For your Google API Key go to: https://cloud.google.com/
