Re: Getting a sample data set. - Mailing list pgsql-general

From Alban Hertroys
Subject Re: Getting a sample data set.
Date
Msg-id 0A7F7B56-42FF-4079-8A8A-C394E02FBBC9@solfertje.student.utwente.nl
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In response to Re: Getting a sample data set.  ("James B. Byrne" <byrnejb@harte-lyne.ca>)
Responses Re: Getting a sample data set.  (Tom Lane <tgl@sss.pgh.pa.us>)
Re: Getting a sample data set.  ("James B. Byrne" <byrnejb@harte-lyne.ca>)
List pgsql-general
On 18 Jan 2011, at 19:59, James B. Byrne wrote:

>
> On Tue, January 18, 2011 13:23, Alban Hertroys wrote:
>>
>>
>> Standard SQL alternatives tend to get complex, using self-joins to
>> weed out all the records you don't want (the exact term for such
>> joins escapes me right now, that would help with Googling if you're
>> looking for examples).
>
> Would the term be a grouped self join?

Nope, but some Googling put me on the right track. It's called a correlated subquery.

> I can see the motivation for something like DISTINCT ON.  I take it
> that this syntax is peculiar to PostgreSQL?:


I suppose you meant particular? Yes, definitely. Although I'm sure some would find it peculiar as well :)

Alban Hertroys

--
If you can't see the forest for the trees,
cut the trees and you'll see there is no forest.


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