我在 PHP 中有选择(组合框),在选择一个后,我用数据库中的数据填充第二个。问题是如何在页面重新加载后从第一个组合框中显示我的选择。我有以下代码:
<select name="category" id="category" maxlength="30" onchange="this.form.submit();">
<option value =""></option>
<?php
require_once("config.php");
// Connect to server
$con = mysql_connect($ServerAddress,$ServerUser,$ServerPassword);
//choose DB
mysql_select_db($DbName, $con);
$sql = "SELECT * FROM `category` ORDER BY `name`";
$res = mysql_query($sql);
while ($row1 = mysql_fetch_array($res)){
echo '<option value ="'.$row1['name'].'">'.$row1['name'].'</option>';
}
?>
</select>
</span>
<label>race:</label>
<span>
<select name="race" id="race" maxlength="30" >
<option value =""></option>
<?php
if (isset($_POST['category'])) {
$var = $_POST['category'];
// Connect to server
$con = mysql_connect($ServerAddress,$ServerUser,$ServerPassword);
//choose DB
mysql_select_db($DbName, $con);
$sql = "SELECT * FROM `race` WHERE `category`='" . sqlSecure($var) . "'ORDER BY `race`";
$res = mysql_query($sql);
while ($row1 = mysql_fetch_array($res)){
echo '<option value ="'.$row1['race'].'">'.$row1['race'].'</option>';
}
}
?>
</select>