Second-hand recycling website uses multi-level classification and screening function developed in PHP

The second-hand recycling website uses the multi-level classification and filtering function developed by PHP

In modern society, people are paying more and more attention to environmental protection, and second-hand recycling has become a popular consumer concept. In order to facilitate users to quickly find the second-hand items they need, many second-hand recycling websites have begun to pay attention to multi-level classification and filtering functions. This article will introduce how to use PHP to develop multi-level classification filtering functions and provide corresponding code examples.

First, we need to design the database table structure to store classification information. Suppose we have the following three tables: categories, subcategories, and items.

CREATE TABLE categories (
    id INT PRIMARY KEY AUTO_INCREMENT,
    name VARCHAR(50) NOT NULL
);

CREATE TABLE subcategories (
    id INT PRIMARY KEY AUTO_INCREMENT,
    category_id INT NOT NULL,
    name VARCHAR(50) NOT NULL,
    FOREIGN KEY (category_id) REFERENCES categories (id)
);

CREATE TABLE items (
    id INT PRIMARY KEY AUTO_INCREMENT,
    subcategory_id INT NOT NULL,
    name VARCHAR(100) NOT NULL,
    price DECIMAL(10, 2) NOT NULL,
    FOREIGN KEY (subcategory_id) REFERENCES subcategories (id)
);

On the front end of the web page, we can use HTML and CSS to create multi-level category selectors. First, we need to create a select element so that the user can select the first-level category:

<label for="category">选择分类：</label>
<select id="category" name="category">
    <option value="">请选择分类</option>
    <?php
        // 获取所有一级分类
        $query = "SELECT * FROM categories";
        $result = mysqli_query($conn, $query);
        while ($row = mysqli_fetch_assoc($result)) {
            echo '<option value="' . $row["id"] . '">' . $row["name"] . '</option>';
        }
    ?>
</select>

When the user selects the first-level category, we can use AJAX to request the second-level category associated with the first-level category from the server:

$(document).ready(function() {
    $("#category").change(function() {
        var categoryID = $(this).val();
        $.ajax({
            url: "get_subcategories.php",
            type: "POST",
            data: { category_id: categoryID },
            success: function(response) {
                $("#subcategory").html(response);
            }
        });
    });
});

On the server side, we create a PHP script (get_subcategories.php) that handles AJAX requests and returns the secondary category options associated with the specified primary category:

<?php
    // 获取一级分类 ID
    $categoryID = $_POST["category_id"];

    // 获取相关的二级分类
    $query = "SELECT * FROM subcategories WHERE category_id = $categoryID";
    $result = mysqli_query($conn, $query);

    // 生成二级分类选项
    echo '<option value="">请选择二级分类</option>';
    while ($row = mysqli_fetch_assoc($result)) {
        echo '<option value="' . $row["id"] . '">' . $row["name"] . '</option>';
    }
?>

Next , we can display the corresponding second-hand item list according to the secondary classification selected by the user. On the front end of the web page, we can use a table to display the names and prices of second-hand items:

<table>
    <thead>
        <tr>
            <th>名称</th>
            <th>价格</th>
        </tr>
    </thead>
    <tbody id="item-list">
        <!-- 二手物品列表将通过 AJAX 动态加载到这里 -->
    </tbody>
</table>

When the user selects the secondary category, we can again obtain the information associated with the secondary category from the server through an AJAX request. Second-hand items:

$(document).ready(function() {
    $("#subcategory").change(function() {
        var subcategoryID = $(this).val();
        $.ajax({
            url: "get_items.php",
            type: "POST",
            data: { subcategory_id: subcategoryID },
            success: function(response) {
                $("#item-list").html(response);
            }
        });
    });
});

On the server side, we create a PHP script (get_items.php) that handles AJAX requests and returns a list of second-hand items associated with the specified secondary category:

<?php
    // 获取二级分类 ID
    $subcategoryID = $_POST["subcategory_id"];

    // 获取相关的二手物品
    $query = "SELECT * FROM items WHERE subcategory_id = $subcategoryID";
    $result = mysqli_query($conn, $query);

    // 生成二手物品列表
    while ($row = mysqli_fetch_assoc($result)) {
        echo '<tr>';
        echo '<td>' . $row["name"] . '</td>';
        echo '<td>' . $row["price"] . '</td>';
        echo '</tr>';
    }
?>

Through the above code example, we have implemented a multi-level classification and filtering function for a second-hand recycling website based on PHP. Users can select a first-level category, then select a corresponding second-level category based on the first-level category, and finally display a list of second-hand items associated with the selected second-level category. The development of this kind of function can help users quickly locate the second-hand items they need and improve the usability and user experience of the website.

Of course, the above is just a simple example. In the actual development process, we also need to consider functions such as data filtering and paging loading to improve website performance and user experience. I hope this article can inspire development and help developers implement more comprehensive and complete multi-level classification and filtering functions.

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