Re: grouping subsets

Howdy, Rainer.

Please advice me,

The dates always follow that sequential pattern?

Or can be holes on the dates sequence?

Best,
Oliveiros

----- Original Message -----
From: "Rainer Stengele" <rainer(dot)stengele(at)diplan(dot)de>
To: <pgsql-sql(at)postgresql(dot)org>
Sent: Thursday, July 22, 2010 9:09 AM
Subject: [SQL] grouping subsets

> Hi,
>
> having a table similar to
>
> | 1 | B | [2010-07-15 Do] |
> | 1 | B | [2010-07-16 Fr] |
> |---+---+-----------------|
> | 2 | C | [2010-07-17 Sa] |
> | 2 | C | [2010-07-18 So] |
> |---+---+-----------------|
> | 1 | B | [2010-07-19 Mo] |
> | 1 | B | [2010-07-20 Di] |
> | 1 | B | [2010-07-21 Mi] |
> | 1 | B | [2010-07-22 Do] |
> |---+---+-----------------|
> | 3 | D | [2010-07-23 Fr] |
>
> a simple group by gives me:
>
> | 6 | B |
> | 4 | C |
> | 3 | D |
>
>
> What I want to get is the values grouped by "subset", where a subset is a
> set of rows with identical column until the colum changes.
> Is there a way to get
>
> | 2 | B |
> | 4 | C |
> | 4 | B |
> | 3 | D |
>
> by SQL only?
>
> - Rainer
>
>
>
>
>
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