Re: transposing data for a view

Hi,
I see how your idea could work--the only thing I would change would
be region needs to be scanid on the first line; however,
I'm using PostgreSQL v7.03, so I can not do subqueries within FROM clause.

Other than creating a temporary table, is there a way to
restructure this solution to get around this limitation?

thanks,
jeremy

Arian Prins <prinsarian@zonnet.nl> wrote in message news:<3BDFAD88.6BB058DA@zonnet.nl>...
> H Jeremy Bockholt schreef:
> 
> > I have a generalized table:
> >
> > scanid | region | volume
> > -------------------------
> > 1          A      34.4
> > 1          B      32.1
> > 1          C      29.1
> > 2          A      32.4
> > 2          B      33.2
> > 2          C      35.6
> > .
> > .
> > .
> >
> > I want to create a flattened out view that looks like the following:
> >
> > scanid | A_volume | B_volume | C_volume
> > ----------------------------------------
> > 1        34.4         32.1      29.1
> > 2        32.4         33.2      35.6
> > .
> > .
> > .
> >
> > How do I correctly/efficiently construct a psql query to
> > pivot/transpose the data?  I am using postgreSQL version 7.0.x
> >
> > thanks,
> > Jeremy
> 
> Try This:
> 
> select region, sum(a_volume) AS a_volume,
>                      sum(b_volume) AS b_volume,
>                     sum(c_volume) AS c_volume
> from (
>     select
>         scanid,
>         volume AS a_volume,
>         0 AS b_volume,
>         0 AS c_volume
>     from mytable
>     where region = A
>     UNION
>     select
>         scanid,
>         0 AS a_volume,
>         volume AS b_volume,
>         0 AS c_volume
>     from mytable
>     where region = B
>     UNION
>     select
>         scanid,
>        0 AS a_volume,
>         0 AS b_volume,
>         volume AS c_volume
>     from mytable
>     where region = C
>  ) tmp
> 
> (you might have to specifically typecast the zero's)
> 
> It would probably also be possible using CASE-statements. This is just
> _one_ idea.
> 
> Arian.