使用php+JS制作二级菜单导航

<iframe src=”city.php” width=”300″ height=”22″ frameborder=”0″ scrolling=”no”></iframe> <input name=”city” type=”hidden” id=”city” value=”" />

<script language=”javascript” type=”text/javascript”> 
function goto(n){ 
this.location.href=”city.php?sh_id=”+n; 
} 
</script> 

<select name=”sh” onchange=”goto(this.value)”> 
<option>请选择所在省市</option> 
<?php 
include_once(”db.php”); 
$sql=”select * from province order by sh_id asc”; 
$result=mysql_query($sql); 
while($row=mysql_fetch_assoc($result)){ 
?> 
<option value=”<? echo $row[”sh_id”];?>” <? if($_GET[”sh_id”]==$row[”sh_id”]){echo 'selected=”selected”‘;}?>><? echo $row[”sh_name”];?></option> 
<?php 
} 
?> 
</select> 
<select name=”city” onchange=”parent.document.getElementById('city').value=this.value”> 
<option>选择你所在的城市</option> 
<?php 
if(!empty($_GET[”sh_id”])){ 
//echo “ok”; 
$sql=”select * from city where sh_id=”.$_GET[”sh_id”].” order by city_id asc”; 
$result=mysql_query($sql); 
while($row=mysql_fetch_assoc($result)){ 
?> 
<option value=”<? echo $row[”city_name”];?>”><? echo $row[”city_name”];?></option> 
<?php 
} 
} 
?> 
</select>