The numeric ranges 0-10 and 10-19 overlap, just as the time ranges
00:01:00-00:00:02:00 overlaps 00:02:00-00:03:00.
*It's the programmer's responsibility* to say what s/he really means, not
for "the system" to make that choice.
On 10/15/21 1:27 PM, Brian Dunavant wrote:
Think of it this way. When someone says they have a meeting from 1-2 and
another from 2-3, do those meetings overlap? They do not, because we're
actually saying the first meeting is from 1:00 through 1:59:59.99999.
The Postgres date ranges are the same way. The starting point is
inclusive, but the ending time is exclusive. So [1:00,2:00), and
[2:00,3:00), do not overlap.
On Fri, Oct 15, 2021 at 2:16 PM Ron <ronljohnso...@gmail.com
<mailto:ronljohnso...@gmail.com>> wrote:
On 10/15/21 8:59 AM, Adrian Klaver wrote:
> On 10/15/21 06:52, Ron wrote:
>> On 10/14/21 7:02 PM, Adrian Klaver wrote:
>> [snip]
>>> or the third example in the docs:
>>>
>>> SELECT (DATE '2001-02-16', DATE '2001-12-21') OVERLAPS
>>> (DATE '2001-10-30', DATE '2002-10-30');
>>> Result: true
>>> SELECT (DATE '2001-02-16', INTERVAL '100 days') OVERLAPS
>>> (DATE '2001-10-30', DATE '2002-10-30');
>>> Result: false
>>> SELECT (DATE '2001-10-29', DATE '2001-10-30') OVERLAPS
>>> (DATE '2001-10-30', DATE '2001-10-31');
>>> Result: false
>>
>> Why /don't/ they overlap, given that they share a common date?
>
> Per the docs:
>
> https://www.postgresql.org/docs/current/functions-datetime.html
<https://www.postgresql.org/docs/current/functions-datetime.html>
>
> " Each time period is considered to represent the half-open interval
start
> <= time < end, unless start and end are equal in which case it
represents
> that single time instant."
>
> Which I read as
>
> (DATE '2001-10-29', DATE '2001-10-30') ends at '2001-10-29'
>
> and
>
> (DATE '2001-10-30', DATE '2001-10-31') starts at DATE '2001-10-30'
>
> so no overlap.
I was afraid you were going to say that. It's completely bizarre, but
seems
to be a "thing" in computer science.
--
Angular momentum makes the world go 'round.
--
Angular momentum makes the world go 'round.
