Comment by zh217

Sqlite supports recursive queries. It is clumsy and not too easy to write, but it works.

For syncing, what I did was to implement a simple automatic backup logic. Then if I want to move to a new device, I just copy the backup I want, which is just a sqlite db file, and restore it. It is not ideal if you are moving from device to device constantly, but it has the benefit that you can compare backups to see what exactly you have changed (I even wrote a tool to build graph visualizations from the output of sqldiff).