From: | Mike Castle <dalgoda(at)ix(dot)netcom(dot)com> |
---|---|
To: | pgsql-novice(at)postgresql(dot)org |
Cc: | Mike Castle <dalgoda(at)ix(dot)netcom(dot)com> |
Subject: | Re: tinterval or interval |
Date: | 2000-11-24 23:20:53 |
Message-ID: | 20001124172053.A1011@thune.mrc-home.org |
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Thread: | |
Lists: | pgsql-novice |
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(at)ix(dot)netcom(dot)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
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