PHP实现基于下拉选择的特定数据库行图片上传教程

<div class="box1">
    <form action='includes/upload.php' method='POST' enctype='multipart/form-data'>
        <select name='book_id_selected' class="books-title">
            <option selected disabled>-- 请选择书籍 --</option>
            <?php
            // 假设 $connection 是已建立的数据库连接
            $sql = 'SELECT `book_id`, `book_title` FROM `books`';
            $result = $connection->query($sql);
            if ($result) {
                while ($row = $result->fetch_object()) {
                    // 将 book_id 作为 option 的 value，book_title 作为显示文本
                    printf('<option value="%s">%s</option>', htmlspecialchars($row->book_id), htmlspecialchars($row->book_title));
                }
            } else {
                echo "<option disabled>无法加载书籍</option>";
            }
            ?>
        </select>   
        <input type='file' name='file' class='uploadImg' />
        <button type='submit' name='submitImg'>上传图片</button>
    </form>
</div>

<?php
// 假设 $connection 是已建立的数据库连接
// 引入数据库连接文件等必要配置
// require_once 'db_connection.php'; 

if ($_SERVER['REQUEST_METHOD'] == 'POST' && isset($_POST['submitImg'])) {
    // 检查是否选择了书籍ID和文件
    if (!isset($_POST['book_id_selected']) || empty($_POST['book_id_selected'])) {
        header("Location: ../index.php?uploadstatus=nobookselected");
        exit();
    }
    if (!isset($_FILES['file']) || $_FILES['file']['error'] == UPLOAD_ERR_NO_FILE) {
        header("Location: ../index.php?uploadstatus=nofile");
        exit();
    }

    $bookId = (int)$_POST['book_id_selected']; // 获取选中的书籍ID

    $file = $_FILES['file'];
    $fileName = $file['name'];
    $fileTmpName = $file['tmp_name'];
    $fileSize = $file['size'];
    $fileError = $file['error'];
    $fileType = $file['type'];

    $fileExt = strtolower(pathinfo($fileName, PATHINFO_EXTENSION)); // 获取文件扩展名

    $allowedExtensions = array('jpg', 'jpeg', 'png', 'gif'); // 允许的图片类型

    // 文件验证
    if (!in_array($fileExt, $allowedExtensions)) {
        header("Location: ../index.php?uploadstatus=invalidtype");
        exit();
    }

    if ($fileError !== UPLOAD_ERR_OK) {
        header("Location: ../index.php?uploadstatus=uploaderror");
        exit();
    }

    // 设置最大文件大小（例如：1MB = 1024 * 1024 字节）
    $maxFileSize = 1024 * 1024; 
    if ($fileSize > $maxFileSize) {
        header("Location: ../index.php?uploadstatus=filesizeexceeded");
        exit();
    }

    // 生成唯一的文件名，以 book_id 和原始文件名为基础
    // 这样可以确保文件名与书籍关联，且避免同名冲突
    $newFileName = $bookId . '_' . uniqid() . '.' . $fileExt; 
    $uploadDirectory = '../../images/book_image/'; // 上传目录

    // 确保上传目录存在且可写
    if (!is_dir($uploadDirectory)) {
        mkdir($uploadDirectory, 0777, true);
    }

    $fileDestination = $uploadDirectory . $newFileName;

    // 移动上传的文件
    if (move_uploaded_file($fileTmpName, $fileDestination)) {
        // 文件上传成功，更新数据库
        $sql = 'UPDATE `books` SET `book_picture` = ? WHERE `book_id` = ?';
        $stmt = $connection->prepare($sql);

        if ($stmt) {
            // 绑定参数，'ss' 表示两个参数都是字符串类型
            $stmt->bind_param('si', $fileDestination, $bookId); 
            $stmt->execute();

            if ($stmt->affected_rows > 0) {
                header("Location: ../index.php?uploadstatus=success");
            } else {
                header("Location: ../index.php?uploadstatus=dbnotupdated");
            }
            $stmt->close();
        } else {
            // 预处理语句失败
            header("Location: ../index.php?uploadstatus=preparefail");
        }
    } else {
        header("Location: ../index.php?uploadstatus=movefail");
    }
    exit();
} else {
    header("Location: ../index.php?uploadstatus=invalidrequest");
    exit();
}
?>

-- 示例：`books` 表结构
CREATE TABLE `books` (
    `book_id` INT(11) NOT NULL AUTO_INCREMENT,
    `book_title` VARCHAR(255) NOT NULL,
    `book_picture` VARCHAR(255) DEFAULT NULL, -- 用于存储图片路径的新字段
    PRIMARY KEY (`book_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;