<parameter>portalName</parameter> can be <literal>""</literal> or
        <symbol>NULL</symbol> to reference the unnamed portal. It is fine
        if no portal exists with this name, in that case the operation is a
        no-op. On success, a <structname>PGresult</structname> with status
        <literal>PGRES_COMMAND_OK</literal> is returned.
       </para>
      </listitem>
     </varlistentry>
    </variablelist>
   </para>

   <para>
    The <structname>PGresult</structname><indexterm><primary>PGresult</primary></indexterm>
    structure encapsulates the result returned by the server.
    <application>libpq</application> application programmers should be
    careful to maintain the <structname>PGresult</structname> abstraction.
    Use the accessor functions below to get at the contents of
    <structname>PGresult</structname>.  Avoid directly referencing the
    fields of the <structname>PGresult</structname> structure because they
    are subject to change in the future.

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

      <listitem>
       <para>
        Returns the result status of the command.
<synopsis>
ExecStatusType PQresultStatus(const PGresult *res);
</synopsis>
       </para>

       <para>
        <xref linkend="libpq-PQresultStatus"/> can return one of the following values:

        <variablelist>
         <varlistentry id="libpq-pgres-empty-query">
          <term><literal>PGRES_EMPTY_QUERY</literal></term>
          <listitem>
           <para>
            The string sent to the server was empty.
           </para>
          </listitem>
         </varlistentry>

         <varlistentry id="libpq-pgres-command-ok">
          <term><literal>PGRES_COMMAND_OK</literal></term>
          <listitem>
           <para>
            Successful completion of a command returning no data.
           </para>
          </listitem>
         </varlistentry>

         <varlistentry id="libpq-pgres-tuples-ok">
          <term><literal>PGRES_TUPLES_OK</literal></term>
          <listitem>
           <para>
            Successful completion of a command returning data (such as
            a <command>SELECT</command> or <command>SHOW</command>).
           </para>
          </listitem>
         </varlistentry>

         <varlistentry id="libpq-pgres-copy-out">
          <term><literal>PGRES_COPY_OUT</literal></term>
          <listitem>
           <para>
            Copy Out (from server) data transfer started.
           </para>
          </listitem>
         </varlistentry>

         <varlistentry id="libpq-pgres-copy-in">
          <term><literal>PGRES_COPY_IN</literal></term>
          <listitem>
           <para>
            Copy In (to server) data transfer started.
           </para>
          </listitem>
         </varlistentry>

         <varlistentry id="libpq-pgres-bad-response">
          <term><literal>PGRES_BAD_RESPONSE</literal></term>
          <listitem>
           <para>
            The server's response was not understood.
           </para>
          </listitem>
         </varlistentry>

         <varlistentry id="libpq-pgres-nonfatal-error">
          <term><literal>PGRES_NONFATAL_ERROR</literal></term>
          <listitem>
           <para>
            A nonfatal error (a notice or warning) occurred.
           </para>
          </listitem>
         </varlistentry>

         <varlistentry id="libpq-pgres-fatal-error">
          <term><literal>PGRES_FATAL_ERROR</literal></term>
          <listitem>
           <para>
            A fatal error occurred.
           </para>
          </listitem>
         </varlistentry>

         <varlistentry id="libpq-pgres-copy-both">
          <term><literal>PGRES_COPY_BOTH</literal></term>
          <listitem>
           <para>
            Copy In/Out (to and from server) data transfer started.  This
            feature is currently used only for