[sqlite] Difference between 2 dates in SQLite

The SQLite documentation is a great reference and the DateAndTimeFunctions page is a good one to bookmark.

It's also helpful to remember that it's pretty easy to play with queries with the sqlite command line utility:

sqlite> select julianday(datetime('now'));
2454788.09219907
sqlite> select datetime(julianday(datetime('now')));
2008-11-17 14:13:55