Re: the '::' cast doesn't work in the FROM clause

On Mon, Aug 29, 2011 at 7:49 AM, Kevin Grittner
<Kevin(dot)Grittner(at)wicourts(dot)gov> wrote:
> Alexey Klyukin  wrote:
>
>> The following statement produces an error message in PostgreSQL 8.4
>> - 9.2 (head):
>>
>> postgres=# select val from random()::integer as val;
>
>> The same statement rewritten with CAST AS works as expected:
>>
>> postgres=# select val from CAST(random() as integer) as val;
>
>> The documentation says these casts are equivalent, so either that's
>> wrong, or this is a bug.
>
> Please point out where you think the documentation says that.  The
> way I read it, this is the correct syntax:
>
> test=# select val from (select random()::integer) as x(val);
>  val
> -----
>   1
> (1 row)
>
> Not only are you missing required parentheses and the SELECT keyword,
> you're returning a record rather than a scalar value.

yeah, that's the correct way, but why does this work?
select val from random() as val;

That's illegal IMO, and walls you off from syntax (like::) you
normally should be able to use.

merlin