Can we use Google Cloud SQL off Google App Engine ?
I'm also looking for examples of its use.
Yes, but you have to use the custom JDBC driver. https://developers.google.com/cloud-sql/docs/external You should expect high latency since your client will not be colocated with the mysqld.
You can also use the JDBC driver for admin tools: https://developers.google.com/cloud-sql/docs/admin_tools