Código PHP:
<form id="formpcc" name="formpcc" method="post" action="">
<input type="text" name="nombre" id="nombre" />
<?php
include "conexion.php";
conectar();
$consulta=mysql_query("SELECT Rubro FROM Rubros");
echo "<select name='rubro'id='rubro' style='text-transform:uppercase'>";
echo "<option value='0'>Elige..</option>";
while($registro=mysql_fetch_array($consulta))
{
echo "<option value='".$registro['Rubro']."'>".$registro['Rubro']."</option>";
}
echo "</select>";
desconectar();
?>
<input name="razonsocial" type="text" id="razonsocial" maxlength="50" />
<input type="text" name="tels" id="tels" />
<textarea name="observaciones" id="observaciones" cols="20" rows="2"></textarea>
<input type="submit" name="Enviar" id="Enviar" value="Guardar" onclick="Cerrar_Ventana()" /