我是PHP的新手，我发现很难真正理解我的代码中的问题，请任何人帮助我。此处附上了我为此目的创建的三个类，我也试图找出我做错了什么，但是我是PHP编码的新手。任何帮助或建议，将不胜感激。谢谢。
<?php
include_once("../../database/constants.php");
?>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8" />
<meta name="viewport" content="width=device-width, initial-scale=1">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<!-- Favicon -->
<link rel="icon" href="../../favicon.ico" type="image/x-icon">
<!-- Google Fonts -->
<link href="https://fonts.googleapis.com/css?family=Open+Sans:400,600,700" rel="stylesheet">
<link href="https://fonts.googleapis.com/icon?family=Material+Icons" rel="stylesheet" type="text/css">
<!-- Bootstrap Core Css -->
<link href="../../assets/plugins/bootstrap/dist/css/bootstrap.css" rel="stylesheet" />
<!-- Animate.css Css -->
<link href="../../assets/plugins/animate-css/animate.css" rel="stylesheet" />
<!-- Font Awesome Css -->
<link href="../../assets/plugins/font-awesome/css/font-awesome.min.css" rel="stylesheet" />
<!-- iCheck Css -->
<link href="../../assets/plugins/iCheck/skins/flat/_all.css" rel="stylesheet" />
<!-- Switchery Css -->
<link href="../../assets/plugins/switchery/dist/switchery.css" rel="stylesheet" />
<!-- Metis Menu Css -->
<link href="../../assets/plugins/metisMenu/dist/metisMenu.css" rel="stylesheet" />
<!-- Jquery Datatables Css -->
<link href="../../assets/plugins/DataTables/media/css/dataTables.bootstrap.css" rel="stylesheet" />
<!-- Pace Loader Css -->
<link href="../../assets/plugins/pace/themes/white/pace-theme-flash.css" rel="stylesheet" />
<!-- Custom Css -->
<link href="../../assets/css/style.css" rel="stylesheet" />
<!-- AdminBSB Themes. You can choose a theme from css/themes instead of get all themes -->
<link href="../../assets/css/themes/allthemes.css" rel="stylesheet" />
<!-- Custom JS -->
<script type="text/javascript" src="../../assets/js/pages/dashboard/main.js"></script>
<!-- Demo Purpose Only -->
<link href="../../assets/css/demo/setting-box.css" rel="stylesheet" />
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.3/jquery.min.js"></script>
<script type="text/javascript">
window.load=$( document ).ready(function() {
$.ajax({
type:'POST',
url:'http://localhost/Alixia/database/ajax_populate/categoryAjaxData.php',
success:function(html){
$('#select_cat').html(html);
}
});
});
$( document ).ready(function() {
$('#select_cat').on('change',function(){//change function on category to display all brand
var categoryID = $(this).val();
if(categoryID){
$.ajax({
type:'POST',
url:'http://localhost/Alixia/database/ajax_populate/categoryAjaxData.php',
data:'cid='+categoryID,
success:function(html){
$('#select_brand').html(html);
$('#select_product').html('<option value="">Select brand first</option>');
}
});
}else{
$('#select_brand').html('<option value="">Select category first</option>');
$('#select_product').html('<option value="">Select brand first</option>');
}
});
$('#select_brand').on('change',function(){//change brand to display all product
var brandID = $(this).val();
if(brandID){
$.ajax({
type:'POST',
url:'ajaxData.php',
data:'bid='+brandID,
success:function(html){
$('#select_product').html(html);
}
});
}else{
$('#select_product').html('<option value="">Select brand first</option>');
}
});
});
</script>
</head>
<body>
<div class="all-content-wrapper">
<!-- Top Bar -->
<header>
<?php include_once("../../build/top-bar.php");?>
</header>
<!-- #END# Top Bar -->
<!-- Left Menu -->
<?php include_once("../../build/left-menu.php");?>
<!-- #END# Left Menu -->
<!-- Right Sidebar -->
<?php include_once("../../build/right-sidebar.php");?>
<!-- #END# Right Sidebar -->
<section class="content dashboard">
<div class="page-heading">
<h1>Manage Products</h1>
</div>
<div class="page-body">
<div class="row clearfix">
<!-- e-commerce card form-->
<div class="container">
<div class="row">
<div class="col-md-10 mx-auto">
<div class="card">
<div class="card-body">
<form>
<div class="form-row">
<div class="form-group col-md-6">
<input type="hidden" name="pid" id="pid" value=""/>
<label>Date</label>
<input type="text" class="form-control" name="added_date" id="added_date" value="<?php echo date("Y-m-d"); ?>" readonly/>
</div>
<div class="form-group col-md-6">
<label>Product Name</label>
<input type="text" class="form-control" name="update_product" id="update_product" placeholder="Enter Product Name" required>
</div>
</div>
<div class="form-row">
<div class="form-group col-md-6">
<label>Product Category</label>
<select class="chosen selectpicker form-control" data-live-search="true" id="select_cat" name="select_cat" required>
<option value="" default selected>Select Category</option>
</select>
</div>
<div class="form-group col-md-6">
<label>Product Brand</label>
<select class="selectpicker form-control" id="select_brand" name="select_brand" required>
<option value="" default selected>Select Brand</option>
</select>
</div>
</div>
<div class="form-row">
<div class="form-group col-md-6">
<label>Product Price</label>
<input type="text" class="form-control" id="product_price" name="product_price" placeholder="Enter Price of Product" required/>
</div>
<div class="form-group col-md-6">
<label>Product Quantity</label>
<input type="text" class="form-control" id="product_qty" name="product_qty" placeholder="Enter Quantity" required/>
</div>
<div class="form-group col-md-6">
<button type="submit" class="btn btn-success"><i class="fa fa-plus"> </i>Add Product</button>
</div>
</div>
</form>
</div>
</div>
</div>
</div>
</div>
<br>
<!-----#END# e-commerce carf form ---->
<?php
//Products Form
//include_once("modal_add_products.php");
?>
<?php
//Products Form
//include_once("manage_modal_products.php");
?>
<!-- #END# Category -->
<!-- To-Do List -->
<!-- #END# To-Do List -->
</div>
<!-- Product Table -->
<div class="panel panel-default">
<div class="panel-heading">Product LIST</div>
<div class="panel-body">
<div class="table-responsive">
<table class="table js-exportable">
<thead>
<tr>
<th>#</th>
<th>Product</th>
<th>Category</th>
<th>Brand</th>
<th>Price</th>
<th>Stock</th>
<th>Added Date</th>
<th>Status</th>
<th>Action</th>
</tr>
</thead>
<tbody id="get_product">
</tbody>
</table>
</div>
</div>
</div>
</div>
<!-- #END# Product table -->
</div>
</section>
<!-- Footer -->
<footer>
<?php include_once("../../build/footer.php");?>
</footer>
<!-- #END# Footer -->
</div>
<!-- Jquery Core Js -->
<script src="../../assets/plugins/jquery/dist/jquery.min.js"></script>
<script type="text/javascript" src="https://code.jquery.com/jquery-3.2.1.min.js"></script>
<!-- JQuery UI Js -->
<script src="../../assets/plugins/jquery-ui/jquery-ui.js"></script>
<!-- Bootstrap Core Js -->
<script src="../../assets/plugins/bootstrap/dist/js/bootstrap.min.js"></script>
<!-- Pace Loader Js -->
<script src="../../assets/plugins/pace/pace.js"></script>
<!-- Screenfull Js -->
<script src="../../assets/plugins/screenfull/src/screenfull.js"></script>
<!-- Metis Menu Js -->
<script src="../../assets/plugins/metisMenu/dist/metisMenu.js"></script>
<!-- Jquery Slimscroll Js -->
<script src="../../assets/plugins/jquery-slimscroll/jquery.slimscroll.js"></script>
<!-- Switchery Js -->
<script src="../../assets/plugins/switchery/dist/switchery.js"></script>
<!-- iCheck Js -->
<script src="../../assets/plugins/iCheck/icheck.js"></script>
<!-- Jquery Sparkline Js -->
<script src="../../assets/plugins/jquery-sparkline/dist/jquery.sparkline.js"></script>
<!-- Flot Chart Js -->
<script src="../../assets/plugins/flot/jquery.flot.js"></script>
<script src="../../assets/plugins/flot-spline/js/jquery.flot.spline.js"></script>
<script src="../../assets/plugins/flot/jquery.flot.pie.js"></script>
<script src="../../assets/plugins/flot/jquery.flot.categories.js"></script>
<script src="../../assets/plugins/flot/jquery.flot.time.js"></script>
<!-- JQuery Datatables Js -->
<script src="../../assets/plugins/DataTables/media/js/jquery.dataTables.js"></script>
<script src="../../assets/plugins/DataTables/media/js/dataTables.bootstrap.js"></script>
<script src="../../assets/plugins/DataTables/extensions/export/dataTables.buttons.min.js"></script>
<script src="../../assets/plugins/DataTables/extensions/export/buttons.bootstrap.min.js"></script>
<script src="../../assets/plugins/DataTables/extensions/export/buttons.flash.min.js"></script>
<script src="../../assets/plugins/DataTables/extensions/export/jszip.min.js"></script>
<script src="../../assets/plugins/DataTables/extensions/export/pdfmake.min.js"></script>
<script src="../../assets/plugins/DataTables/extensions/export/vfs_fonts.js"></script>
<script src="../../assets/plugins/DataTables/extensions/export/buttons.html5.min.js"></script>
<script src="../../assets/plugins/DataTables/extensions/export/buttons.print.min.js"></script>
<!-- Piety Js -->
<script src="../../assets/plugins/peity/jquery.peity.js"></script>
<!-- Custom Js -->
<script src="../../assets/js/admin.js"></script>
<script src="../../assets/js/pages/dashboard/dashboard.js"></script>
<!-- Google Analytics Code -->
<script src="../../assets/js/google-analytics.js"></script>
<!-- Demo Purpose Only -->
<script src="../../assets/js/demo.js"></script>
</body>
</html>
<?php
//fetch all country data from database
//Include database configuration file
include('../Alixia/database/db.php');
$query = $mysqli->query("SELECT * FROM categories WHERE status = 1 ORDER BY category_name ASC");// select all categories from database
//Count total number of rows
$rowCount = $query->num_rows;
//Display states list
if($rowCount > 0)
{
echo '<option value="">Select Category</option>';// initial message display{
//echo '<input type="text" >';// initial message display
while($row = $query->fetch_assoc())
{
echo '<option value="'.$row['cid'].'">'.$row['category_name'].'</option>';// select category id & name from country table
}
}
else
{
echo '<option value="">Category Not Available</option>'; //display when no data!
}
?>
<?php
//Include database configuration file
include('../Alixia/database/db.php');
if(isset($_POST["cid"]) && !empty($_POST["cid"])){
//Get all brand data
$query = $mysqli->query("SELECT * FROM brands WHERE cid = ".$_POST['cid']." AND status = 1 ORDER BY brand_name ASC");
//Count total number of rows
$rowCount = $query->num_rows;
//Display product list
if($rowCount > 0){
echo '<option value="">Select brand</option>';
while($row = $query->fetch_assoc()){
echo '<option value="'.$row['bid'].'">'.$row['brand_name'].'</option>';
}
}else{
echo '<option value="">Brand not available</option>';
}
}
if(isset($_POST["bid"]) && !empty($_POST["bid"])){
//Get all product data
echo "asdasd";
$query = $mysqli->query("SELECT * FROM products WHERE bid = ".$_POST['bid']." AND status = 1 ORDER BY product_name ASC");
//Count total number of rows
$rowCount = $query->num_rows;
//Display Product list
if($rowCount > 0){
echo '<option value="">Select product</option>';
while($row = $query->fetch_assoc()){
echo '<option value="'.$row['pid'].'">'.$row['product_name'].'</option>';
}
}else{
echo '<option value="">Product not available</option>';
}
}
?>
我尝试使用和编辑我在网上看到的Ajax代码，该代码似乎正在处理我在youtube上观看的视频，但对我没有帮助，请问我对这些代码有什么误解。