>From 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 has
>to come from somewhere and that location is the from/join part of the query.
In your query foo.work_date is not a literal or function and so must be sourced
from somewhere. 2011-11-20 is a literal being fed into a function and so does
not require a From clause in order to be evaluated.
David J.
On Dec 17, 2011, at 11:50, John Fabiani <jo...@jfcomputer.com> wrote:
> As always I respect your insights - Adrian. I do understand what I did wrong
> in my first attempt at getting my statement to work. But it is either over
> my
> head or there is something missing. Where is the "from" in
> select now()?
>
> I have been using similar SQL statements for years. I never questioned why
> there was not a 'from' until this list noted that I was missing a 'From'. I
> then went to the postgres site to read. That's how I determined what I had
> done incorrectly.
>
> I hope this is not one of those things like javascript where all white space
> is ignored unless it's not! I hate that language! It appears that
> everything
> needs a 'From' in SQL (reading the doc's) and the above statement is missing
> a
> 'From'!
>
> As always everyone - thanks for your help!
>
> Johnf
>
>
> On Friday, December 16, 2011 07:31:40 AM Adrian Klaver wrote:
>> FROM Clause
>> "select
>>
>> 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 parentheses,
>> and an alias must be provided for it. A VALUES command can also be used
>> here. "
>>
>>>
>>>
>>> select foo.week_date, xchromasun._chromasun_getqtyordered(303,
>>> foo.week_date) as week_qty from
>>>
>>> (select ((date_trunc('week', '2011-11-20'::date )::date) + (i+6)) as
>>>
>>> week_date from generate_series(0,84,7)
>>>
>>> i ) as foo
>>>
>>>
>>> The above works!
>
> --
> Sent via pgsql-sql mailing list (pgsql-sql@postgresql.org)
> To make changes to your subscription:
> http://www.postgresql.org/mailpref/pgsql-sql
--
Sent via pgsql-sql mailing list (pgsql-sql@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-sql
