Re: fetch first rows of grouped data
От | D'Arcy J.M. Cain |
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Тема | Re: fetch first rows of grouped data |
Дата | |
Msg-id | 20070827141552.21ec3a54.darcy@druid.net обсуждение исходный текст |
Ответ на | Re: fetch first rows of grouped data (Joel Richard <postgres@joelrichard.com>) |
Список | pgsql-sql |
On Mon, 27 Aug 2007 13:34:09 -0400 Joel Richard <postgres@joelrichard.com> wrote: > That's what I thought at first, but this is not the case. She's > looking for the first two dates in -each- city in the table. I > initially thought that this could be accomplished with GROUP BY and > LIMIT, but GROUP BY can only give you the first date for each city, > not the first two dates for each city. Yes, you are correct. My mistake. > So far, I haven't come up with any clever ideas. I'm not sure this > can be done in SQL. Well, I can think of an SQL only method involving a temporary table but it would not be a single query: - Select into temp table where date is max.- Select from temp table union with main table where date is max and is not in temp table. -- D'Arcy J.M. Cain <darcy@druid.net> | Democracy is three wolves http://www.druid.net/darcy/ | and a sheep voting on +1 416 425 1212 (DoD#0082) (eNTP) | what's for dinner.
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