php 二级级联菜单

找了很多个级联的菜单，都不好用，自己弄个简单点的，共享下，希望有朋友用得着

<?php

//建立表country,有三个字段Id,parentId,area.

$pro = $_POST['pre'];

$cit = $_POST['city'];

echo $pro;

echo $cit;

$link = mysql_connect("localhost","root","wanwei");

if (!$link)

   die("链接服务器失败.".mysql_error());

$db = mysql_select_db("aiiee",$link);

if(!$db)

   die("选择数据库失败.".mysql_error());

$str = "select * from country where parentId != 0";

mysql_query("set names 'gbk'");

$result = mysql_query($str,$link);

$rownum = mysql_num_rows($result);

$row = mysql_fetch_array($result);

?>

<script language="JavaScript">

var _option = new Array(); //建立一个一维数组 _option.



<?php

for($i=0;$i<$rownum;$i++){  

   echo "_option[".$i."] = new Array('".$row["area"]."',".$row["id"].",".$row["parentId"].")\n"; //用数组 _option 的元素建立二维数组,第一列是city的text,第二列是city自身Id,第三列是city的父级Id.

   $row = mysql_fetch_array($result);

}

?>



function ChangeSelect(SelfId){

    document.form_category.city.length = 0;  //初始化市级下拉列表长度为零.

        document.form_category.city.options[0] = new Option('==请选择市==','0'); //把市级下拉列表的第一个option设为0.

    for(i=0;i < _option.length;i++){ //在二维数组 _option 内循环,当第i行,第3列的值等于SelfId时,就用第i行,第1列的来建立city的option.

          if(_option[i][2] == SelfId){

             document.form_category.city.options[document.form_category.city.length] = new Option(_option[i][0],_option[i][1]);
//建立city的option.

          }       

        }

}



</script>

<form name="form_category" id="form_category" method="post" action="test.php">          

        <select name="pre" id="pre" onChange="ChangeSelect(this.value);">

         <option>==请选省/市==</option>                  

        <?php

         $rs_result = mysql_query("select * from country where parentId=0",$link);

         $row_num = mysql_num_rows($rs_result);

         $rs_row = mysql_fetch_array($rs_result);

         for($m=1;$m<=$row_num;$m++){

         ?>

          <option value="<?=$rs_row["id"]?>"><?=$rs_row["area"]?></option>

        <?php

          $rs_row = mysql_fetch_array($rs_result);

         }

         ?>               

        </select>

               

        <select name="city" id="city">        

      <option>==请选择市==</option>

        </select>       

        <input type="submit">                

</form>

<?php

mysql_close($link);

?>