I know that App Engine has its own datastore. This is great for most cases and fairly easy to used. However, we have a MySQL database that we use for several applications an
I am still in the learning phase of all this, but I am fairly certain you can do this now a few ways:
"Google Apps Script has the ability to make connections to databases via JDBC with the Jdbc Service. The current support extends to MySQL, Microsoft SQL Server and Oracle. Apps Script makes it easy to connect to databases hosted on Google Cloud SQL, but also works with other cloud hosting platforms and even local databases." https://developers.google.com/apps-script/jdbc
(origionally from App Engine Question)