vitqst/index.php

## index.php
<?php
   include_once 'dbconfig.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=iso-8859-1" />
      <title> test </title>
      <script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.3/jquery.min.js"></script>
      <script type="text/javascript">
 		$(document).ready(function(){
 			$(".type").change(function()
 			{
  				var type_top = $(this).val();

  				var dataString = 'type_top='+ type_top;
 				alert(dataString);
  				$.ajax({
   					type: "POST",
   					url: "type_child.php",
   					data: dataString,
   					cache: false,
   					success: function(html){
     	 				$(".type_child").html(html);
   					}
   				});
  			});
 		});
	</script>

   </head>
   <body>
      <center>
         <div>
            <label> THỂ LOẠI :</label>
            <select name="country" class="type">
               <option selected="selected">-----    Chọn thể loại    --</option>
               <?php
                  $query = "SELECT * FROM type" ;
                  $result = mysqli_query($connection,$query) ;

                 		while($row = mysqli_fetch_array($result) )
                  		{
                ?>
               					<option value="<?php echo $row['type_tag']; ?>"><?php echo $row['type_name']; ?></option>
               		<?php
                  		}
                  	?>
            </select>
            <br>
            <label>THỂ LOẠI CON :</label>
            <select name="state" class="type_child">
				<option selected="">-- Chọn thể loại con --</option>
			</select>
         </div>
         <br />
      </center>
   </body>
</html>
	<?php
	include_once 'dbconfig.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=iso-8859-1" />
	<title> test </title>
	<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.3/jquery.min.js"></script>
	<script type="text/javascript">
	$(document).ready(function(){
	$(".type").change(function()
	{
	var type_top = $(this).val();

	var dataString = 'type_top='+ type_top;
	alert(dataString);
	$.ajax({
	type: "POST",
	url: "type_child.php",
	data: dataString,
	cache: false,
	success: function(html){
	$(".type_child").html(html);
	}
	});
	});
	});
	</script>

	</head>
	<body>
	<center>
	<div>
	<label> THỂ LOẠI :</label>
	<select name="country" class="type">
	<option selected="selected">----- Chọn thể loại --</option>
	<?php
	$query = "SELECT * FROM type" ;
	$result = mysqli_query($connection,$query) ;

	while($row = mysqli_fetch_array($result) )
	{
	?>
	<option value="<?php echo $row['type_tag']; ?>"><?php echo $row['type_name']; ?></option>
	<?php
	}
	?>
	</select>
	<br>
	<label>THỂ LOẠI CON :</label>
	<select name="state" class="type_child">
	<option selected="">-- Chọn thể loại con --</option>
	</select>
	</div>
	<br />
	</center>
	</body>
	</html>