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From: Josh Kupershmidt <[email protected]>
To: pgsql-docs <[email protected]>
Subject: example for PGRES_COMMAND_OK
Date: Fri, 26 Oct 2012 16:58:13 -0700
Message-ID: <CAK3UJRG262OrX4jVZJXvWRFQqQ_B1HaY2qK_r28Efb3wOJDPog@mail.gmail.com> (raw)

Hi all,

This libpq page:
  http://www.postgresql.org/docs/current/static/libpq-exec.html#LIBPQ-PQRESULTSTATUS

has claimed since at least the 7.x days:
| PGRES_COMMAND_OK is for commands that can never return rows (INSERT,
UPDATE, etc.)

However, as of 8.2 we support the popular INSERT ... RETURNING and
UPDATE ... RETURNING, both of which will naturally give a successful
PQresultStatus() of PGRES_TUPLES_OK. So I think this explanation
deserves an amendment. We could just change the example commands to
e.g. TRUNCATE for simplicity, but I do like that the current example
commands are INSERT and UPDATE, since it reinforces the notion that a
plain INSERT or UPDATE affecting no rows would still return
PGRES_COMMAND_OK.

Suggested change attached.

Josh


Attachments:

  [application/octet-stream] libpq.PGRES_COMMAND_OK.diff (1.1K, 2-libpq.PGRES_COMMAND_OK.diff)
  download | inline diff:
diff --git a/doc/src/sgml/libpq.sgml b/doc/src/sgml/libpq.sgml
new file mode 100644
index 255c5c1..a6a179e
*** a/doc/src/sgml/libpq.sgml
--- b/doc/src/sgml/libpq.sgml
*************** ExecStatusType PQresultStatus(const PGre
*** 2445,2451 ****
          command that happens to retrieve zero rows still shows
          <literal>PGRES_TUPLES_OK</literal>.
          <literal>PGRES_COMMAND_OK</literal> is for commands that can never
!         return rows (<command>INSERT</command>, <command>UPDATE</command>,
          etc.). A response of <literal>PGRES_EMPTY_QUERY</literal> might
          indicate a bug in the client software.
         </para>
--- 2445,2452 ----
          command that happens to retrieve zero rows still shows
          <literal>PGRES_TUPLES_OK</literal>.
          <literal>PGRES_COMMAND_OK</literal> is for commands that can never
!         return rows (<command>INSERT</command> or <command>UPDATE</command>
!         without a <literal>RETURNING</literal> clause,
          etc.). A response of <literal>PGRES_EMPTY_QUERY</literal> might
          indicate a bug in the client software.
         </para>

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