原始问题：<select> 下拉菜单使用 JS 函数正确输出我的 MYSQL 数据
我试图写一篇后续文章，但将其添加为答案。这是我的问题：
使用与 MassiveAttack 相似/相同的脚本；我的问题是，一旦我选择第二个下拉菜单，这两个下拉菜单就会自行重置（URL 正确）；我如何“保持”我的价值观？
这是我的脚本：
function reload(form) {
var val=form.cat.value;
var val2=form.subcat.value;
self.location='dd.php?cat=' + val + '&subcat=' + val2;
}
</script>
</head>
<body>
<?
@$cat = $_GET ['cat']; // Use this line or below line if register_global is off
if (strlen ( $cat ) > 0 and ! is_numeric ( $cat )) { // to check if $cat is
// numeric data
// or not.
echo "Cat Data Error";
exit ();
}
$quer2 = mysql_query ( "SELECT DISTINCT name,category_id FROM shop_categories order by name" );
// ///// for second drop down list we will check if category is selected else we
// will display all the subcategory/////
if (isset ( $cat ) and strlen ( $cat ) > 0) {
$quer = mysql_query ( "SELECT name,product_id,priority,description FROM products WHERE category_id=$cat order by name" );
} else {
$quer = mysql_query ( "SELECT name,product_id,priority,description FROM products order by name" );
}
// //////// end of query for second subcategory drop down list box
echo "<form method=post name=f1 action='dd-check.php'>";
// / Add your form processing page address to action in above line. Example
// action=dd-check.php////
// //////// Starting of first drop downlist /////////
echo "<select name='cat' onchange=\"reload(this.form)\"><option value=''>Select Category</option>";
while ( $noticia2 = mysql_fetch_array ( $quer2 ) ) {
if ($noticia2 ['category_id'] == @$cat) {
echo "<option selected value='$noticia2[name]'>$noticia2[name]</option>" . "<BR>";
} else {
echo "<option value='$noticia2[category_id]'>$noticia2[name]</option>";
}
}
echo "</select>";
// //////////////// This will end the first drop down list ///////////
// //////// Starting of second drop downlist /////////
$myList1 = array ();
echo "<select name='subcat' onchange=\"reload(this.form)\"><option value=''>Select subCategory</option>";
while ( $noticia = mysql_fetch_array ( $quer ) ) {
if ($_GET ['subcat'] == $noticia [subcat]) {
echo "<option value='$noticia[name]'>$noticia[name]</option>";
}
}
echo "</select>";
echo "<input type=submit value=Submit>";
echo "</form>";
?>
</body>
</html>
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