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Cc: "pgsql-sql@postgresql.org" <pgsql-sql@postgresql.org>
From: David Johnston <polobo@yahoo.com>
Subject: Re: using a generated series in function
Date: Sat, 17 Dec 2011 13:10:40 -0500
To: John Fabiani <johnf@jfcomputer.com>

=46rom is not required if you use literals or function results (with literal=
 input parameters).  If you reference something that is not one of these it h=
as to come from somewhere and that location is the from/join part of the que=
ry.

In your query foo.work_date is not a literal or function and so must be sour=
ced from somewhere.  2011-11-20 is a literal being fed into a function and s=
o does not require a =46rom clause in order to be evaluated.

David J.

On Dec 17, 2011, at 11:50, John Fabiani <johnf@jfcomputer.com> wrote:

> As always I respect your insights - Adrian.  I do understand what I did wr=
ong=20
> in my first attempt at getting my statement to work.  But it is either ove=
r my=20
> head or there is something missing.  Where is the "from" in
> select now()?
>=20
> I have been using similar SQL statements for years.  I never questioned wh=
y=20
> there was not a 'from' until this list noted that I was missing a 'From'. =
  I=20
> then went to the postgres site to read.  That's how I determined what I ha=
d=20
> done incorrectly.
>=20
> I hope this is not one of those things like javascript where all white spa=
ce=20
> is ignored unless it's not!  I hate that language!  It appears that everyt=
hing=20
> needs a 'From' in SQL (reading the doc's) and the above statement is missi=
ng a=20
> 'From'!
>=20
> As always everyone - thanks for your help!
>=20
> Johnf
>=20
>=20
> On Friday, December 16, 2011 07:31:40 AM Adrian Klaver wrote:
>> FROM Clause
>> "select
>>=20
>>    A sub-SELECT can appear in the FROM clause. This acts as though its
>> output  were created as a temporary table for the duration of this single=

>> SELECT command. Note that the sub-SELECT must be surrounded by parenthese=
s,
>> and an alias must be provided for it. A VALUES command can also be used
>> here. "
>>=20
>>>=20
>>>=20
>>> select foo.week_date, xchromasun._chromasun_getqtyordered(303,
>>> foo.week_date) as week_qty from
>>>=20
>>> (select ((date_trunc('week', '2011-11-20'::date )::date) + (i+6)) as
>>>=20
>>> week_date from generate_series(0,84,7)
>>>=20
>>> i ) as foo
>>>=20
>>>=20
>>> The above works!
>=20
> --=20
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