Re: Docs claim that "select myTable.*" wildcard won't let you assign column names

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