Re: problem selecting multiple records (again!)
От | Manuel Sugawara |
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Тема | Re: problem selecting multiple records (again!) |
Дата | |
Msg-id | m3g0de37th.fsf@dep1.fciencias.unam.mx обсуждение исходный текст |
Ответ на | problem selecting multiple records (again!) ("Giorgio Andreoletti - mentelocale" <giorgio.andreoletti@mentelocale.it>) |
Ответы |
Re: problem selecting multiple records (again!)
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Список | pgsql-novice |
something like select * from events where ref in (select distinct ref from events limit 3); will do what you want. hth, Manuel. "Giorgio Andreoletti - mentelocale" <giorgio.andreoletti@mentelocale.it> writes: > hi everyone, > i already wrote to this list for the same problem.... i thought i had > resolved it, but i was wrong ! > i'll explain my problem in a different (and simplier to understand) way: > > suppose you have a table representing some events like this: > > id | ref | date > ----------------------- > 1 | 10 | 2001-05-10 > 2 | 10 | 2001-05-11 > 3 | 10 | 2001-05-12 > 4 | 20 | 2001-05-11 > 5 | 20 | 2001-05-13 > 6 | 30 | 2001-05-15 > > the "ref" field is used to match this table with an another table containing > the description of the event in that date. > So, in this example I have the same event (identified as '10') which is > repeated 3 times, another event ('20') repeated twice, and an event with a > single occurance ('30'). > now suppose that today is 2001-05-09 and i want to publish on my web-site > the next 3 events: > > doing a simple SELECT i will get : > > 1 | 10 | 2001-05-10 > 2 | 10 | 2001-05-11 > 4 | 20 | 2001-05-11 > > but what i really wanted was : > > 1 | 10 | 2001-05-10 > 4 | 20 | 2001-05-11 > 6 | 30 | 2001-05-15 > > i.e., i don't want to get more than one occurance of the same "ref". > > plz help me since i'm getting crazy trying to solve this problem !!! > keep in mind that i'll have a table with hundreds of event, so the faster > way to get the result is the preferred :-) > > the web publishing system is based on zope. > > tnx for your help > > ============================ > Giorgio Andreoletti - mentelocale S.r.l. > responsabile hardware e networking > responsabile sviluppo web > www.mentelocale.it > giorgio.andreoletti@mentelocale.it > ============================ > > > ---------------------------(end of broadcast)--------------------------- > TIP 1: subscribe and unsubscribe commands go to majordomo@postgresql.org
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