sub query and AS

Hi,

I like PostgreSQL for many reasons, one of them is the possibility to
use sub query everywhere. Now I've found where it doesn't support them.

I would like to use a AS (sub query) form.

This is an example:

First the subquery:

select substr(descr, 7, length(descr)-8)
from (select string_agg('" int,"',freephone) as descr
from (select distinct freephone
from calendario order by 1
) as a
) as b;

substr

-----------------------------------------------------------------------------------------------------------------------------------------------------------------
"800900420" int,"800900450" int,"800900480" int,"800900570"
int,"800900590" int,"800900622" int,"800900630" int,"800900644"
int,"800900688" int,"800900950" int
(1 row)

Then the wishing one:

itv2=#
select *
FROM crosstab('select uscita,freephone,id from calendario order by
1','select distinct freephone from calendario order by 1')
-- following AS fails
AS (select 'uscita int, ' || substr(descr, 7, length(descr)-8)
from (select string_agg('" int,"',freephone) as descr
from (select distinct freephone
from calendario order by 1) as a
) as b;
);
ERROR: syntax error at or near "select"
LINE 4: ...stinct freephone from calendario order by 1') as (select 'us...

More is on http://paste.scsys.co.uk/198877

I think that AS must evaluate the sub query in advance.

It could be possible to have such behavior?

Best regards, \ferz