On Monday, September 21, 2015, Amir Rohan <amir.rohan@mail.com> wrote:
>> From http://www.postgresql.org/docs/9.4/static/sql-select.html[http://www.postgresql.org/docs/9.4/static/sql->>
select.html](and previous version too):
>>
>> ##SELECT List
>>
>> <...>
>> Instead of an expression, * can be written in the output list as a shorthand for all the columns of the
>> selected rows.
>> Also, you can write table_name.* as a shorthand for the columns coming from just that table. In these
>> cases it is not possible to specify new names with AS; the output column names will be the same as the
>> table columns' names.
>>
>> But, the docs elsewhere feature a query example show the use of a wildcard for columns
>> as well as allowing you to assign names to as many of the leading columns as you wish:
>>
>>
>> WITH T0 as ( SELECT 1,2,3 )
>> SELECT T0.* from T0 as T0(foo,bar) ;<...>
On Monday, September 21, 2015, David G. Johnston wrote:
> Neither of those examples is:
>
> SELECT * AS "how would one alias this?" FROM table
>
> So what's your point?
My point is that "In these cases it is not possible to specify new names with AS" is misleading because
it *is* possible and useful, but requires syntax which isn't clearly shown (if at all) where I'd expect it.
I think that could be improved.
> Obviously you can alias stuff before it makes its way into a select-list that refers to it using *
"obvious" to whom? probably not to someone who's level of SQL mastery has brought him/her to reading
the exciting "SELECT" documentation. I do see your point though, in the grammar the "AS" in my example
belongs not to `output_name ` but to `from_item`. So this syntax is hidden away behind the `column_alias`
production.
> In this case the FROM clause is what is being aliased. It is documented though I'd need to look to
> identify the specific location.
This belongs in the page describing SELECT, and though I've looked I haven't found it. If I'm wrong (
I did look again just now), please correct me.
Amir