Subtracting time fields - Mailing list pgsql-sql

Hello all,

I have two fields in my database access_time and release_time.....I
would like to calculate the "duration" between these two values, but
can't figure out what to do.  

I've tried something like this but it doesn't work:

select access_time, release_time, time(access_time) - time(release_time)
as duration from mastertbl limit 10

Any suggestions?

Thanks,
Kevin
-- 
Kevin Old <kold@carolina.rr.com>