On Wed, 2003-10-08 at 14:31, Chris Boget wrote:
> noob alert.
>
> > SELECT * FROM oldtable WHERE false;
>
> What exactly is this doing? What is the 'WHERE false' doing for the
> query?
"WHERE false" ensures that no rows are selected. When combined with
SELECT INTO (as I believe the original message suggested) the end result
is to create a new table with the same columns as oldtable but with no
rows:
junk=# select * from xxx;
id | xx
----+--------
1 | ????????????
(1 row)
junk=# select * into zzz FROM xxx WHERE false;
SELECT
junk=# select * from zzz;
id | xx
----+----
(0 rows)
But note that the table structure is not exactly the same:
junk=# \d xxx
Table "public.xxx"
Column | Type | Modifiers
--------+---------+-----------------------------------------------------
id | integer | not null default nextval('public.xxx_id_seq'::text)
xx | text | not null
Indexes:
"xxx_pkey" primary key, btree (id)
junk=# \d zzz
Table "public.zzz"
Column | Type | Modifiers
--------+---------+-----------
id | integer |
xx | text |
--
Oliver Elphick Oliver.Elphick@lfix.co.uk
Isle of Wight, UK http://www.lfix.co.uk/oliver
GPG: 1024D/3E1D0C1C: CA12 09E0 E8D5 8870 5839 932A 614D 4C34 3E1D 0C1C
========================================
"Let no man say when he is tempted, I am tempted of
God; for God cannot be tempted with evil, neither
tempteth he any man; But every man is tempted, when he
is drawn away of his own lust, and enticed."
James 1:13,14
