On Fri, Nov 24, 2000 at 02:52:31PM -0600, Mike Castle wrote:
> Am I missing something in the documentation that would explain to me how I
> could use a starttime/length combination (something like abstime/interval,
> or timestamp/interval) to check for overlaps like can be done with tinterval?
Ok. Apparently it's time to invest in a good SQL book before proceeding.
I did a web search and found SQL specs online (well, not the final
versions, but probably close enough).
And I figured out how to use the overlaps operator:
test=# select ('2000-11-21 08:00'::timestamp, '2000-11-21 09:00'::timestamp)
overlaps ('2000-11-21 08:59'::timestamp, '2000-11-21 10:00'::timestamp);
overlaps
----------
t
(1 row)
Probably an easier way to write that, but in the mean time....
I have noticed a difference between how overlaps work compared to && for
tinterval. With tinterval [8:00-9:00] is considered to overlap with
[9:00-10:00], while with overlaps, they don't:
test=# select tinterval '["2000-11-21 08:00" "2000-11-21 09:00"]' &&
tinterval '["2000-11-21 09:00" "2000-11-21 10:00"]';
?column?
----------
t
(1 row)
test=# select ('2000-11-21 08:00'::timestamp, '2000-11-21 09:00'::timestamp)
overlaps ('2000-11-21 09:00'::timestamp, '2000-11-21 10:00'::timestamp);
overlaps
----------
f
(1 row)
Since I don't yet have a good book.... should that be considered to overlap
or not? My initial thoughts were that tinterval and timestamps/overlaps
would have the same semantics.
mrc
--
Mike Castle Life is like a clock: You can work constantly
dalgoda@ix.netcom.com and be right all the time, or not work at all
www.netcom.com/~dalgoda/ and be right at least twice a day. -- mrc
We are all of us living in the shadow of Manhattan. -- Watchmen
