The <structname>PGresult</structname> represents a pipeline that has
            received an error from the server.  <function>PQgetResult</function>
            must be called repeatedly, and each time it will return this status code
            until the end of the current pipeline, at which point it will return
            <literal>PGRES_PIPELINE_SYNC</literal> and normal processing can
            resume.
           </para>
          </listitem>
         </varlistentry>

        </variablelist>

        If the result status is <literal>PGRES_TUPLES_OK</literal>,
        <literal>PGRES_SINGLE_TUPLE</literal>, or
        <literal>PGRES_TUPLES_CHUNK</literal>, then
        the functions described below can be used to retrieve the rows
        returned by the query.  Note that a <command>SELECT</command>
        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>

       <para>
        A result of status <symbol>PGRES_NONFATAL_ERROR</symbol> will
        never be returned directly by <xref linkend="libpq-PQexec"/> or other
        query execution functions; results of this kind are instead passed
        to the notice processor (see <xref
        linkend="libpq-notice-processing"/>).
       </para>
      </listitem>
     </varlistentry>

     <varlistentry id="libpq-PQresStatus">
      <term><function>PQresStatus</function><indexterm><primary>PQresStatus</primary></indexterm></term>

      <listitem>
       <para>
        Converts the enumerated type returned by
        <xref linkend="libpq-PQresultStatus"/> into a string constant describing the
        status code. The caller should not free the result.

<synopsis>
char *PQresStatus(ExecStatusType status);
</synopsis>
       </para>
      </listitem>
     </varlistentry>

     <varlistentry id="libpq-PQresultErrorMessage">
      <term><function>PQresultErrorMessage</function><indexterm><primary>PQresultErrorMessage</primary></indexterm></term>

      <listitem>
       <para>
        Returns the error message associated with the command, or an empty string
        if there was no error.
<synopsis>
char *PQresultErrorMessage(const PGresult *res);
</synopsis>
        If there was an error, the returned string will include a trailing
        newline.  The caller should not free the result directly. It will
        be freed when the associated <structname>PGresult</structname> handle is
        passed to <xref linkend="libpq-PQclear"/>.
       </para>

       <para>
        Immediately following a <xref linkend="libpq-PQexec"/> or
        <xref linkend="libpq-PQgetResult"/> call,
        <xref linkend="libpq-PQerrorMessage"/> (on the connection) will return
        the same string as <xref linkend="libpq-PQresultErrorMessage"/> (on
        the result).  However, a <structname>PGresult</structname> will
        retain its error message until destroyed, whereas the connection's
        error message will change when subsequent operations are done.
        Use <xref linkend="libpq-PQresultErrorMessage"/> when you want to
        know the status associated with a particular
        <structname>PGresult</structname>; use
        <xref linkend="libpq-PQerrorMessage"/> when you want to know the
        status from the latest operation on the connection.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry id="libpq-PQresultVerboseErrorMessage">
      <term><function>PQresultVerboseErrorMessage</function><indexterm><primary>PQresultVerboseErrorMessage</primary></indexterm></term>

      <listitem>
       <para>
        Returns a reformatted version of the error message associated with