Re: R: One column to multiple columns based on constraints?
От | BillR |
---|---|
Тема | Re: R: One column to multiple columns based on constraints? |
Дата | |
Msg-id | 004a01caaa01$7b92ade0$72b809a0$@com обсуждение исходный текст |
Ответ на | Re: R: One column to multiple columns based on constraints? ("Davor J." <DavorJ@live.com>) |
Список | pgsql-general |
Is there any reason it has to be done in one DML statement? Can you write a procedure to this in multiple steps?
BillR
From: pgsql-general-owner@postgresql.org [mailto:pgsql-general-owner@postgresql.org] On Behalf Of Davor J.
Sent: February-09-10 2:02 PM
To: pgsql-general@postgresql.org
Subject: Re: [GENERAL] R: One column to multiple columns based on constraints?
Crosstab is indeed very interesting. Thank you for the suggestion Vincenzo.
regards
Davor
"Vincenzo Romano" <vincenzo.romano@notorand.it> wrote in message news:3eff28921002081133h4b0d7fabm96cc1bc08e5794dc@mail.gmail.com...
Look for crosstab in the documentation.
Il giorno 8 feb, 2010 8:21 p., "Davor J." <DavorJ@live.com> ha scritto:
Let's say you have a table:
CREATE TABLE t (
time date,
data integer
)
Suppose you want a new table that has columns similar to the following:
"(x.time, x.data, y.time, y.data, z.time, z.data)" where x.time, y.time and
z.time columns are constrained (for example x.time >2007 AND x.time <2008,
y.time >2008 AND y.time < 2009, z.time > 2010)
How would you do this. Note that you can not use JOIN as there is no
relationship.
Currently I came up with something like this:
SELECT X.*, (SELECT Y.time, Y.data FROM t AS Y WHERE Y.time = X.time + 1),
(SELECT Z.time .) FROM t AS X WHERE X.time >2007 AND X.time <2008
But it's somewhat awkward. I thought maybe someone has better idea's. Any
input is welcome.
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