Aqui esta el codigo
config.inc.php<?
define("_host", "localhost");
define("_user", " root");
define("_password", " ******");
define("_database", "base");
?>
mysql.class.php<?php
class MySQL{
private $conexion;
private $total_consultas;
public function open(){
if(!isset($this->conexion)){
$this->conexion = (mysql_connect(_host,_user,_password)) or die(mysql_error());
mysql_select_db(_database,$this->conexion) or die(mysql_error());
}
}
public function consulta($consulta){
$this->total_consultas++;
$resultado = mysql_query($consulta,$this->conexion);
if(!$resultado){
echo 'MySQL Error: ' . mysql_error().'<br>'.$consulta;
exit;
}
return $resultado;
}
public function fetch_array($consulta){
return mysql_fetch_array($consulta);
}
public function num_rows($consulta){
return mysql_num_rows($consulta);
}
public function getTotalConsultas(){
return $this->total_consultas;
}
public function close(){
if ($this->conexion){
return mysql_close($this->conexion);
}
}
}
?>
index.php
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<meta name="keywords" content="ajax, combos, dependientes, jquery" />
<meta name="description" content="Demo para crear combos dependiente usando jquery (Ajax)" />
<title>Combos dependientes</title>
<script language="javascript" src="js/jquery-1.3.min.js"></script>
<script language="javascript">
$(document).ready(function(){
// Parametros para e combo1
$("#combo1").change(function () {
$("#combo1 option:selected").each(function () {
//alert($(this).val());
elegido=$(this).val();
$.post("combo1.php", { elegido: elegido }, function(data){
$("#combo2").html(data);
$("#combo3").html("");
});
});
})
// Parametros para el combo2
$("#combo2").change(function () {
$("#combo2 option:selected").each(function () {
//alert($(this).val());
elegido=$(this).val();
$.post("combo2.php", { elegido: elegido }, function(data){
$("#combo3").html(data);
});
});
})
});
</script>
</head>
<body>
<?php
include("includes/config.inc.php");
include("includes/mysql.class.php");
?>
<table width="400" align="center">
<tr><td>
<select name="combo1" id="combo1">
<option value="0">Elija uno</option>
<?php
$db = new MySQL();
$db->open();
$consulta = $db->consulta("SELECT * FROM carrera");
if ($row = $db->fetch_array($consulta)) {
do {
echo
'<option value="'.$row[clave].'">'.$row[carrera].'</option>';
}while($row = $db->fetch_array($consulta));
}
?>
</select>
<br />
<select name="combo2" id="combo2">
</select>
<br />
<select name="combo3" id="combo3">
</select>
<p align="center">
<a href="http://www.miguelmanchego.com/2009/combos-dependientes-ajax-base-de-datos/">Ver el codigo del ejemplo</a>
</p>
</td></tr></table>
</body>
</html>
combo1.php
<?php
include("includes/config.inc.php");
include("includes/mysql.class.php");
$db = new MySQL();
$db->open();
$consulta = $db->consulta("SELECT * FROM materia WHERE clave_m LIKE '$_POST[elegido]'");
if ($row = $db->fetch_array($consulta)) {
do {
echo
'<option value="'.$row['clave_m'].'">'.$row['materia'].'</option>';
}while($row = $db->fetch_array($consulta));
}
?>