RowDescription message

Hi,

On 2019-10-07 17:00:24 +0900, Tatsuo Ishii wrote:

According to the manualof RowDescription message
https://www.postgresql.org/docs/12/protocol-message-formats.html

Specifies the number of fields in a row (can be zero).

Does 0 fields could actually happen?

Yes, e.g.:

SELECT;

According to the manualof RowDescription message
https://www.postgresql.org/docs/12/protocol-message-formats.html

Specifies the number of fields in a row (can be zero).

Does 0 fields could actually happen?

Yes, e.g.:

SELECT;

Thanks. Is it a valid SQL statement according to the standard?

Best regards,
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese:http://www.sraoss.co.jp

Tatsuo Ishii <ishii@sraoss.co.jp> writes:

According to the manualof RowDescription message
https://www.postgresql.org/docs/12/protocol-message-formats.html
Specifies the number of fields in a row (can be zero).
Does 0 fields could actually happen?

Yes, e.g.:
SELECT;

Thanks. Is it a valid SQL statement according to the standard?

See select.sgml:

<refsect2>
<title>Empty <literal>SELECT</literal> Lists</title>

<para>
The list of output expressions after <literal>SELECT</literal> can be
empty, producing a zero-column result table.
This is not valid syntax according to the SQL standard.
<productname>PostgreSQL</productname> allows it to be consistent with
allowing zero-column tables.
However, an empty list is not allowed when <literal>DISTINCT</literal> is used.
</para>
</refsect2>

regards, tom lane

Or
CREATE TABLE t();

SELECT *
FROM t;
________________________________
Van: Tatsuo Ishii <ishii@sraoss.co.jp>
Verzonden: maandag 7 oktober 2019 10:00
Aan: pgsql-general@postgresql.org <pgsql-general@postgresql.org>
Onderwerp: RowDescription message

According to the manualof RowDescription message
https://www.postgresql.org/docs/12/protocol-message-formats.html

Specifies the number of fields in a row (can be zero).

Does 0 fields could actually happen?

Best regards,
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese:http://www.sraoss.co.jp