Re: what does t(x) in select x from generate_series(1, 10) as t(x) stand for?

"David G. Johnston" <david(dot)g(dot)johnston(at)gmail(dot)com> writes:
> On Wednesday, November 8, 2017, john snow <ofbizfanster(at)gmail(dot)com> wrote:
>> is
>> select x from generate_series(1, 10) as t(x);
>> different from
>> select x from generate_series(1, 10) as x;

> Not sure about the pgAdmin part but t(x) means that you are aliasing the
> table result of the generate_series call to the name "t" and that
> tables' first (and in this case only) column is aliased to the name "x".

Right.

> The x in the select is then that first column. In the "as x" variant all
> you've done is alias the table to the name "x" and the "x" in the select
> refers to the table. Not able to confirm right now but the first result
> should yield a column of type bigint while the second should a composite
> whose only column is a bigint and whose name is "generate_series".

Not sure offhand what happens for a function-returning-composite, but
I'm pretty sure that if the function returns a scalar type, then

SELECT ... from f(...) as x;

is treated the same as

SELECT ... from f(...) as x(x);

Experimentally, these all produce identical results:

select x from generate_series(1, 10) as x;
select x.x from generate_series(1, 10) as x;
select x.* from generate_series(1, 10) as x;

which seems to confirm that.

regards, tom lane