One column to multiple columns based on constraints?
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.
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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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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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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To make changes to your subscription:
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I have limited access to the database. I can not write stored procedures, so it has to be pure SQL.
But yes, PL opens other possibilities.
Davor
""BillR"" <iambill@williamrosmus.com> wrote in message news:004a01caaa01$7b92ade0$72b809a0$@com...
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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Davor J. wrote:
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
Um, why can't you use a join?
SELECT X.*, Y.time, Y.data FROM t AS X JOIN t as Y ON (Y.time = X.time + '1 year'::INTERVAL)
WHERE X.time >= '2007-01-01'::DATE AND X.time < '2008-01-01'::DATE;
I believe should be functionally equivalent to your nested select. I'm
not real sure what you're trying to imply with your date > integer
comparisions, so I tried to be a little more rigorous there.
Thank you for the input John.
You understood my sketch just fine and your JOIN is indeed equivalent to the
nested select. I said there is no relationship, but in my nested select I
implicitly created a relationship. I should have been more explicit here:
what I meant is that there "should" be no relationship.
From what I know of SQL, one always needs a relationship to append some row
to the one from FROM clause. I want to append them without a relationship.
So if my base table "t" has columns (time and data), I want a new table
which has columns (time2008, data2008, time2009, data2009, time2010,
data2010,...) where rows of time2009 and data2009 are constrained by 'year
2008' , but are in no relationship with the rows of time2008. (NULL should
be used if there are more in year2008 column, than in year2009 column, vice
versa.)
Regards,
Davor
"John R Pierce" <pierce@hogranch.com> wrote in message
news:4B72729D.7020302@hogranch.com...
Show quoted text
Davor J. wrote:
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 <2008Um, why can't you use a join?
SELECT X.*, Y.time, Y.data FROM t AS X JOIN t as Y ON (Y.time = X.time +
'1 year'::INTERVAL) WHERE X.time >= '2007-01-01'::DATE AND X.time <
'2008-01-01'::DATE;I believe should be functionally equivalent to your nested select. I'm
not real sure what you're trying to imply with your date > integer
comparisions, so I tried to be a little more rigorous there.--
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