>
SELECT (julianday(ended_at)-julianday(started_at)) as duration FROM ...
The duration computed this way will be in days. Multiply by 24.0 to get hours,
or 86400.0 to get seconds, and so forth. Example:
> ~~~
SELECT (julianday('now') - julianday('2000-05-29 14:16')) AS duration;
┌──────────────────┐
│ duration │
├──────────────────┤
│ 7724.33961798623 │
└──────────────────┘
SELECT (julianday('now') - julianday('2000-05-29 14:16'))*86400.0 AS 'duration in seconds';
┌─────────────────────┐
│ duration in seconds │
├─────────────────────┤
│ 667383060.794015 │
└─────────────────────┘
~~~
The SQLite project has been going for a little over 7724 days, or about 667
million seconds.