Re: creating table without columns

Subodh Kumar <subodh(dot)kumar(at)epps-erp(dot)com> writes:
> I have run below query it is created 'test' table without columns
> but table row count is 2.
> please give me clarity about this, i thought it may give syntax error but
> not
> either it must have 2 rows data but both are not happened.

> with ins_test as (select 1 as srno
> union
> select 2)
> select into test from ins_test;

I think you meant to write

with ins_test as (select 1 as srno
union
select 2)
select * into test from ins_test;

or possibly

with ins_test as (select 1 as srno
union
select 2)
select srno into test from ins_test;

What you did write has no columns in the SELECT result clause,
so the INTO creates a table of no columns --- but you get
the expected number of rows.

Postgres allows zero-column tables, and zero-column selects,
because otherwise there are too many weird corner cases;
for instance ALTER TABLE DROP COLUMN would have to reject
dropping the last column. The SQL standard has a different
opinion about which way is less ugly ...

regards, tom lane