Re: Query not producing expected result

Поиск
Список
Период
Сортировка
От Francisco Olarte
Тема Re: Query not producing expected result
Дата
Msg-id CA+bJJbzPv+Wa1CqhOm8ZtV8ZN6z2=OAF1wR=bB8xm0wXyR9QrA@mail.gmail.com
обсуждение исходный текст
Ответ на Re: Query not producing expected result  (Adrian Klaver <adrian.klaver@aklaver.com>)
Ответы Re: Query not producing expected result  (Adrian Klaver <adrian.klaver@aklaver.com>)
Список pgsql-general
Adrian:

On Wed, May 1, 2019 at 7:57 PM Adrian Klaver <adrian.klaver@aklaver.com> wrote:
> You will have to explain further as I am not seeing it:
> test_(postgres)# select '2019-05-01 9:52' <= '2019-05-01 24:00'::timestamp;
>   ?column?
> ----------
>   t
>
> test_(postgres)# select '2019-05-01 24:00' <= '2019-05-01 24:00'::timestamp;
>   ?column?
> ----------
>   t

Because you are using two selected examples. The one with 9:52 is ok.

The last one is misleading because you are using a constant for a
particular timestamp in MAY THE SECOND wich can be written to look
like it is in MAY THE FIRST.

Rewrite it as
select '2019-05-02'::timestamp <= '2019-05-01 24:00'::timestamp;

And you'll see and out of range date selected.

This is why <= AND 24:00 are bad and misleading.

You may not have problems with 00:00:00 times, but work a bit billing
phone calls and you'll find about one in 86400 hit it ( more in my
case as traffic distribution is skewed ). Use that kind of condition
and you end up chasing why the monthly report has a dozen less calls
than the sum of the daily ones the billing guys made using excel.

Francisco Olarte.



В списке pgsql-general по дате отправления:

Предыдущее
От: Adrian Klaver
Дата:
Сообщение: Re: Query not producing expected result
Следующее
От: Francisco Olarte
Дата:
Сообщение: Re: Query not producing expected result