If you check here: http://cordova.apache.org/docs/en/3.3.0/cordova_storage_storage.md.html#Storage , the page clearly shows the Web SQL Database API is being used.
This Web SQL Database API is no longer being maintained as mentioned here: http://dev.w3.org/html5/webdatabase/
Moreoever, the PhoneGap solution for Web SQL Database API is not available on all platforms. On the other hand, they also mention that indexedDB is supported, but on a different set of devices.
Why haven they broken the cross platform norms and also used an API being deprecated?