PHP implements three-level cascading drop-down box, multi-select drop-down box, drop-down box plug-in, drop-down box code

This is the information I found on the Internet about implementing three-level cascading drop-down boxes in PHP. I would like to share it with you so that everyone can make progress together. The specific content is as follows

index.php:

{$arr["name"]}
EOD; }
mysql_close($conn);
?>




 三级分类



 XMLHttpRequest对象的status属性值为200 , html文件在本地运行,则xmlHttp.status的返回值为0,故应该加上xmlHttp.status==0
 if(xmlHttp.status==200 || xmlHttp.status==0)     //调用文档对象模型DOM的getElementById()方法查找html文件中的标签txtHint ,
     //innerHTML为IE浏览器中的属性,可以用来更改标签间文本的内容 ,
     //xmlHttp.responseText , 通过XMLHttpRequest的responseText属性来获取数据 responseText,结果为字符串;responseXML,结果为XML形式
//     document.getElementByIdx_x_xx_x_xx("txtHint").innerHTML=xmlHttp.responseText
     BuildSel(xmlHttp.responseText,document.getElementsByTagName_r("*").sel2)
     showMenu2(document.getElementsByTagName_r("*").sel2.value); }
}
//函数stateChanged() - 响应HTTP请求状态变化
function stateChanged2() //判断XMLHttpRequest对象的readyState属性值是否为4,如果为4表示异步调用完成(注意:异步调用完成 不代表 异步调用成功)
if (xmlHttp2.readyState==4 || xmlHttp2.readyState=="complete") //如果异步调用成功 --> XMLHttpRequest对象的status属性值为200 , html文件在本地运行,则xmlHttp.status的返回值为0,故应该加上xmlHttp.status==0
 if(xmlHttp2.status==200 || xmlHttp2.status==0)     //调用文档对象模型DOM的getElementById()方法查找html文件中的标签txtHint ,
     //innerHTML为IE浏览器中的属性,可以用来更改标签间文本的内容 ,
     //xmlHttp.responseText , 通过XMLHttpRequest的responseText属性来获取数据 responseText,结果为字符串;responseXML,结果为XML形式
//     document.getElementByIdx_x_xx_x_xx("txtHint").innerHTML=xmlHttp.responseText
     BuildSel(xmlHttp2.responseText,document.getElementsByTagName_r("*").sel3) }
}
//函数GetXmlHttpObject() - 创建XMLHttpRequest对象,即创建一个异步调用对象
function GetXmlHttpObject() var xmlHttp=null;
try // Firefox, Opera 8.0+, Safari
 xmlHttp=new XMLHttpRequest(); catch (e) //Internet Explorer
 try  xmlHttp=new ActiveXObject("Msxml2.XMLHTTP"); catch (e)  xmlHttp=new ActiveXObject("Microsoft.XMLHTTP"); }
return xmlHttp; -->
get2.php


<?php header('Content-Type:text/html;charset=GB2312'); $conn = mysql_connect('localhost', 'root', '') or die('Could not connect: ' . mysql_error());
mysql_select_db('fitment', $conn) or die ('Can\'t use database : ' . mysql_error());
mysql_query("set names 'gb2312'");
//如果传递过来q
if($_GET["q"]){
$strs = "SELECT * FROM fitment_sort WHERE supid=' ".$_GET["q"]."' ";
//echo $str;
$results = mysql_query($strs) or die("Invalid query: " . mysql_error());
if($results)   while ($arrs = mysql_fetch_array($results)){
    $strings .= $arrs["id"]."|".$arrs["name"].",";   }
  echo substr($strings,0,strlen($strings)-1); }
//如果传递过来q2
if($_GET["q2"]){
$str = "SELECT * FROM fitment_sort WHERE supid= '".$_GET["q2"]."'";
//echo $str;
$result = mysql_query($str) or die("Invalid query: " . mysql_error());
if($result)   while ($arr = mysql_fetch_array($result)){
    $string .= $arr["id"]."|".$arr["name"].",";   }   echo substr($string,0,strlen($string)-1); }
mysql_close($conn);
?>
 
The above is the relevant code for implementing three-level cascading drop-down boxes in PHP. I hope it will be helpful for everyone to learn PHP programming. 
                
                
                

                    The above introduces the implementation of three-level cascading drop-down boxes in PHP, including the contents of PHP and drop-down boxes. I hope it will be helpful to friends who are interested in PHP tutorials.