Re: DONT_CARE Aggregate
| От | Chris Curvey |
|---|---|
| Тема | Re: DONT_CARE Aggregate |
| Дата | |
| Msg-id | CADfwSsBzN3LcJHi_WjiuHTfQQ56GAuO-6rM5M2-bX38TXwz6aQ@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: DONT_CARE Aggregate (Robert James <srobertjames@gmail.com>) |
| Список | pgsql-general |
On Thu, Dec 20, 2012 at 12:00 PM, Robert James <srobertjames@gmail.com> wrote:
-- I see. What if I need to do this along with an Aggregate Query. Eg
something like:
SELECT x,y,z, MAX(a), MAX(b), DONT_CARE_AS_LONG_AS_NOT_NULL(c),
DONT_CAR_AS_LONG_AS_P_IS_TRUE(d,p)
...
GROUP BY x,y,z
ah, I get what you're trying to do. If you truly don't care about the value of C, then just use MIN() or MAX().
for the conditional part, use a CASE statement, along with MAX or MIN, like this:
SELECT MIN(CASE WHEN P=TRUE THEN D ELSE NULL END)
Because MIN() and MAX() ignore NULL values. (Except for the special case where all the values are null.)
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