下拉动态依赖于另一个动态下拉列表

Question

很抱歉，如果之前已经讨论过，但是基于我的观察和试验。所有这些都不起作用。我有5个下拉菜单，它们是品牌，型号，颜色，引擎号。和chasis no。。我应该使用什么javascript函数，来制作依赖于所选品牌的模型的下拉列表，颜色的下拉取决于所选模型和下拉引擎号。并且chasis no取决于所选择的颜色。

这是我的代码

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	<label for="bName" class="control-label col-xs-4"><p class="left">Brand</p></label>
	<div class="col-xs-7">
	<div class="req">
			<?php
include_once "config.php";

													$bsql="SELECT bName, brandID FROM brand order by bName"; 
			$bstmt=$con->prepare($bsql);
			$bstmt->execute();
		$bstmt->bind_result($bName, $bid);
		$bstmt->store_result();

													echo "<select name='brandID' class='form-control'>
														<option value=''></option>";

													while ($bstmt->fetch()){
 echo '<option value="'.$bid.'">'.$bName.'</option>';
													}

echo '</select>';
?>
			</div>
<div class="col-xs-1">
</div>
</div>
</div>
<div class="form-group">
									
<label for="model" class="control-label col-xs-4"><p class="left">Model</p></label>
<div class="col-xs-7">
<div class="req">	
	
 <?php
include_once "config.php";

													$msql="SELECT model, modID FROM model where brandID=? order by model"; 
$mstmt=$con->prepare($msql);
$mstmt->bind_param('i', $bid)

$mstmt->execute();
$mstmt->bind_result($model, $mid);
$mstmt->store_result();

echo "<select name='mID' class='form-control'>
<option value=''></option>";

while ($mstmt->fetch()){  echo '<option value="'.$mid.'">'.$model.'</option>';
													}
echo '</select>';
												
													?>
													
</div>
  <div class="col-xs-1">
</div>
</div>	
</div>
<div class="form-group">
 <label for="color" class="control-label col-xs-4"><p class="left">Color</p></label>
<div class="col-xs-7">
<select ="color" class="req">
	<option value='blue'>Blue</option>
	<option value='red'>Red</option>
	</select>
	</div>
	<div class="col-xs-1">
	</div>
	</div>
	</div>
	<div class="col-lg-6">
  <div class="form-group">
<label for="engine"  class="control-label col-xs-4"><p class="left">Engine No.</p></label>
<div class="col-xs-7">
<select name="engine"  class="req" required/>
<option></option>
</select>
</div>
<div class="col-xs-1">
</div>
</div>
<div class="form-group">
									
<label for="chasis"  class="control-label col-xs-4"><p class="left">Chasis No.</p></label>
<div class="col-xs-7">
<select name="chasis"  class="req" required/>
<option></option>
												
</select>
</div>
<div class="col-xs-1">
</div>
</div>
</div>
</div>

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