symbol">NULL</code> is it certain that the <a class="xref" href="libpq-exec.html#LIBPQ-PQEXEC"><code class="function">PQexec</code></a>
   command string is done and it is safe to issue more commands.
  </p><p>
   The functions of this section should be executed only after obtaining
   a result status of <code class="literal">PGRES_COPY_OUT</code> or
   <code class="literal">PGRES_COPY_IN</code> from <a class="xref" href="libpq-exec.html#LIBPQ-PQEXEC"><code class="function">PQexec</code></a> or
   <a class=