php+mysql多级联动问题

Question

我的数据表结构是这样的ty_system为数据库名 其中三个表分别为ty_prv，ty_city，ty_road 。ty_prv字段ty_prv_name和ty_prv_id（主键）；ty_city字段ty_city_name ty_city_id（主键）ty_prv_id（外键）；ty_road字段ty_road_name ty_road_id（主键）ty_city_id（外键）。
我想通过php完成多级联动，因为是菜鸟 网上查询了一些代码 求帮检查哪里有问题 页面选择省份之后城市的下拉菜单就变成空的了。<form id="mediaForm" name="mediaForm" action="" method="post" >
<select name ="province" onChange="province2city(this.options[this.selectedIndex].value)">
<option selected value ="">所有省份</option>
<?php require_once('Connections/system.php'); ?>
<?
mysql_select_db($database_system, $system);
$query_Recordset1 = "SELECT * FROM ty_prv";
$Recordset1 = mysql_query($query_Recordset1) ;
$row_Recordset1=mysql_fetch_array($Recordset1);
$totalRows_Recordset1 = mysql_num_rows($Recordset1);
  
?>
<?php
do {  
?>
  <option value="<?=$row_Recordset1["ty_prv_id"];?>">
<?php echo $row_Recordset1["ty_prv_name"];?>
</option>
  <?php
} while ($row_Recordset1 = mysql_fetch_array($Recordset1));
  $rows = mysql_num_rows($Recordset1);
  if($rows > 0) {
      mysql_data_seek($Recordset1, 0);
  $row_Recordset1 = mysql_fetch_array($Recordset1);
  }
?>
<!--
<option value="<?=$row_Recordset1["ty_prv_id"];?>">
<?php echo $row_Recordset1["ty_prv_name"];?>
</option>
--></select>
<select name="city" id="city" onChange="province2city(this.options[this.selectedIndex].value)">
<option selected value="">所有城市</option>
</select>
<select name="road" id="road">
<option selected vaule ="">所有道路</option>
</select></form><script language="JavaScript">
function province2city (provinceid)
{var allcount=0;
cityArray=new Array();
<?php require_once('Connections/system.php'); ?>
<?
mysql_select_db($database_system, $system);
$query_Recordset2 ="select *from ty_city";
$Recordset2 =mysql_query($query_Recordset2);
$count=0;
while ($row_Recordset2 =mysql_fetch_array($Recordset2)){
?>
cityArray[<?=$count?>]=new Array("<?=$row_Recordset2['ty_city_id']?>","<?=$row_Recordset2['ty_city_id']?>","<?=$row_Recordset1['ty_prv_id']?>");
<?
$count++;
}
echo "allcount=$count;";?>
document.mediaForm.city.length=0;
document.mediaForm.city.options[document.mediaForm.subject.length]=new Option ("所有城市","");
var province=province;
var i;
for(i=1;i<allcount;i++)
{if(cityArray[i][2]==province)
{ document.mediaForm.city.options[document.mediaForm.city.length]=new Option(cityArray[i][1],cityArray[i][0]);
}
}
}
</script>