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Date: Mon, 21 Sep 2015 19:39:38 -0400
Message-ID: 
 <CAKFQuwb1pTAh3gGzReSnUAoSobYQmHhy-90rKo82BeVCR7W+Kw@mail.gmail.com>
Subject: Re: Docs claim that "select myTable.*" wildcard won't let you
 assign column names
From: "David G. Johnston" <david.g.johnston@gmail.com>
To: Amir Rohan <amir.rohan@mail.com>
Cc: "pgsql-docs@postgresql.org" <pgsql-docs@postgresql.org>
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On Monday, September 21, 2015, Amir Rohan <amir.rohan@mail.com> wrote:

>
> From 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 wildcar=
d
> 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) ;
>
>  foo =E2=94=82 bar =E2=94=82 ?column?
> =E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=BC=E2=94=80=E2=94=80=
=E2=94=80=E2=94=80=E2=94=80=E2=94=BC=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=
=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80
>    1 =E2=94=82   2 =E2=94=82        3
> (1 row)
>
> The following curious variant also works:
>
> WITH T0 as ( SELECT 1,2,3 )
> SELECT justAnythingReally.* from T0 as justAnythingReally(foo,bar) ;
>
> The synoposis/grammer at the top doesn't hint at this either. I've checke=
d
> and this has been supported since at least 9.2 .
>
>

Neither of those examples is:

SELECT * AS "how would one alias this?" FROM table

So what's your point?  Obviously you can alias stuff before it makes its
way into a select-list that refers to it using *

In this case the FROM clause is what is being alised.  It is documented
though I'd need to look to identify the specific location. It would not be
documented in a section regarding the select-list.

David J.

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On Monday, September 21, 2015, Amir Rohan &lt;<a href=3D"mailto:amir.rohan@=
mail.com">amir.rohan@mail.com</a>&gt; wrote:<br><blockquote class=3D"gmail_=
quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1=
ex"><div><div style=3D"font-family:Verdana;font-size:12.0px"><div>=C2=A0</d=
iv>

<div>From <a href=3D"http://www.postgresql.org/docs/9.4/static/sql-select.h=
tml" target=3D"_blank">http://www.postgresql.org/docs/9.4/static/sql-select=
.html</a> (and previous version too):</div>

<div>
<h3><tt>=C2=A0 ##SELECT</tt> List</h3>

<div>=C2=A0=C2=A0=C2=A0 &lt;...&gt;</div>
</div>

<div>=C2=A0=C2=A0=C2=A0 Instead of an expression, <tt>*</tt> can be written=
 in the output list as a shorthand for all the columns of the selected rows=
.</div>

<div>=C2=A0=C2=A0=C2=A0 Also, you can write <tt><tt>table_name</tt>.*</tt> =
as a shorthand for the columns coming from just that table. In these cases =
it is not</div>

<div>=C2=A0=C2=A0=C2=A0 possible to specify new names with <tt>AS</tt>; the=
 output column names will be the same as the table columns&#39; names.</div=
>

<div>=C2=A0</div>

<div>But,=C2=A0the docs elsewhere feature a query example show the use of a=
 wildcard for columns</div>

<div>as well as allowing you to assign names to as many of the leading colu=
mns as you wish:</div>

<div>=C2=A0
<div>
<div>WITH T0 as ( SELECT 1,2,3 )<br>
SELECT T0.* from T0 as T0(foo,bar) ;</div>

<div>=C2=A0</div>

<div>
<div>=C2=A0foo =E2=94=82 bar =E2=94=82 ?column?<br>
=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=BC=E2=94=80=E2=94=80=E2=
=94=80=E2=94=80=E2=94=80=E2=94=BC=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=
=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80<br>
=C2=A0=C2=A0 1 =E2=94=82=C2=A0=C2=A0 2 =E2=94=82=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0 3<br>
(1 row)</div>

<div>=C2=A0</div>

<div>The following curious variant also works:</div>

<div>=C2=A0</div>

<div>WITH T0 as ( SELECT 1,2,3 )<br>
SELECT justAnythingReally.* from T0 as justAnythingReally(foo,bar) ;</div>
</div>
=C2=A0

<div>The synoposis/grammer at the top doesn&#39;t hint at this either. I=
9;ve checked and this has been supported since at least 9.2 .</div>

<div>=C2=A0</div></div></div></div></div></blockquote><div><br></div><div>N=
either of those examples is:</div><div><br></div><div>SELECT * AS &quot;how=
 would one alias this?&quot; FROM table</div><div><br></div><div>So what=
9;s your point?=C2=A0 Obviously you can alias stuff before it makes its way=
 into a select-list that refers to it using *</div><div><br></div><div>In t=
his case the FROM clause is what is being alised.=C2=A0 It is documented th=
ough I&#39;d need to look to identify the specific location. It=C2=A0would =
not be documented in a section regarding the select-list.</div><div><br></d=
iv><div>David J.</div>

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