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zero-column table behavior

From: Neil Conway <neilc(at)samurai(dot)com>
To: PostgreSQL Developers <pgsql-hackers(at)postgresql(dot)org>
Subject: zero-column table behavior
Date: 2004-05-23 00:28:43
Message-ID: 40AFF03B.7030304@samurai.com (view raw or flat)
Thread:
Lists: pgsql-hackers
Does the following zero-column behavior strike anyone else as being a 
little strange? I can take a look at fixing this, I'm just curious if 
there's a consensus that the status quo isn't optimal.

(1)

neilc=# create table zero_col ();
CREATE TABLE
neilc=# select * from zero_col;

--
(0 rows)

-- Why is there a blank line before the "--" that indicates the
-- end of the result set? That seems inconsistent with the way
-- we present a normal empty result set:

neilc=# create table abc (a int);
CREATE TABLE
neilc=# select * from abc;
  a
---
(0 rows)

(2)

neilc=# insert into zero_col default values;
INSERT 17218 1
neilc=# insert into zero_col default values;
INSERT 17219 1
neilc=# select * from zero_col;

--
(2 rows)

-- If the result set contains two rows, ISTM the psql output
-- should emit either two or three blank lines before the "--"
-- that indicates the end of the result set

(3)

neilc=# select * from zero_col order by random();
ERROR:  ORDER/GROUP BY expression not found in targetlist

-- ISTM that ought to work

(4)

neilc=# create view zero_col_view as select * from zero_col;
ERROR:  view must have at least one column

-- ISTM that ought to work as well: if we allow zero-column tables,
-- is there a good reason for disallowing zero-column views?

-Neil


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