PHP更新分类上传新图时unlink()无法删除旧图片问题求助

unlink() 无法删除旧图片的核心错误是路径拼接缺失目录分隔符：
在code.php的更新逻辑里，你判断旧文件是否存在时用的路径是正确的：

if(file_exists("../uploads/".$old_image))

这行拼接出的路径格式为../uploads/旧文件名.jpg，和你实际存储图片的路径一致。但紧接着执行删除的代码漏写了uploads和文件名之间的/：

unlink("../uploads".$old_image);

这行实际拼接出的路径是../uploads旧文件名.jpg，程序会去上级目录找一个名字以uploads开头、后面直接跟旧图片名的文件，根本定位不到uploads目录里存的旧图，自然删除失败。

直接把unlink那行的路径补全斜杠即可，修改后对应代码段：

if($_FILES['image']['name'] != "")
{
    move_uploaded_file($_FILES['image']['tmp_name'], $path.'/'.$update_filename);

    if(file_exists("../uploads/".$old_image))
    {
        unlink("../uploads/".$old_image);
    }
}

• 调整执行顺序：现有逻辑是先更新数据库里的图片字段，再执行新图移动、旧图删除操作。如果后续移动新文件出错，数据库里已经存了新文件名，会导致前台图片加载404。建议改成先移动新上传的图片，确认移动成功后再更新数据库、删除旧图片。
• 补全安全校验：现有SQL直接拼接POST传入的参数，存在SQL注入风险，建议改用mysqli预处理语句绑定参数执行数据库操作。
• 删除文件前增加非空判断：如果旧图片字段值为空，不要执行unlink操作，避免误删服务器文件。

附相关代码文件参考

edit-category.php #

<?php 
include('includes/header.php');
include('../middleware/adminMiddleware.php');
?>

<!-- Add cards for better UI -->
<div class="container">
    <div class="row">
        <div class="col-md-12"> 
            <?php if(isset($_GET['id'])) { 
                $id = $_GET['id'];  
                $category = getByID("categories", $id);
                if(mysqli_num_rows($category) > 0)
                {
                    $data = mysqli_fetch_array($category);
            ?>
                    <div class="card">
                        <div class="card-header">
                            <h4>Edit Category </h4>
                        </div>
                        <div class="card-body">
                            <form action="code.php" method="POST" enctype="multipart/form-data">
                                <div class="row">
                                    <div class="col-md-6">
                                        <label for="">Name</label>
                                        <input type="hidden" name="category_id" value="<?= $data['id'] ?>" class="form-control" placeholder="Enter Category Name" >
                                        <input type="text" name="name" value="<?= $data['name'] ?>" class="form-control" placeholder="Enter Category Name" >
                                    </div>
                                    <div class="col-md-6">
                                        <label for="">Slug</label>
                                        <input type="text" name="slug" value="<?= $data['slug'] ?>" class="form-control" placeholder="Enter Slug">
                                    </div>
                                    <div class="col-md-12">
                                        <label for="">Description</label>
                                        <textarea rows="3" name="description" class="form-control" placeholder="Enter Description"> <?= $data['description'] ?></textarea>
                                    </div>
                                    <div class="col-md-12">
                                        <label for="">Upload Image</label>
                                        <input type="file" name="image" class="form-control">
                                        <label for="">Current Image</label>
                                        <input type="hidden" name="old_image" value="<?= $data['image'] ?>">
                                        <img src="../uploads/<?= $data['image'] ?>" alt="" height="100px" width="100px">
                                    </div>
                                    <div class="col-md-12">
                                        <label for="">Meta Title</label>
                                        <input type="text" name="meta_title" value="<?= $data['meta_title'] ?>" class="form-control" placeholder="Enter Title">
                                    </div>
                                    <div class="col-md-12">
                                        <label for="">Meta Description</label>
                                        <textarea rows="3" name="meta_description" class="form-control" placeholder="Enter Meta Description"><?= $data['meta_description'] ?></textarea>
                                    </div>
                                    <div class="col-md-12">
                                        <label for="">Meta Keywords</label>
                                        <textarea rows="3" name="meta_keywords" class="form-control" placeholder="Enter Keywords"><?= $data['meta_keywords'] ?></textarea>
                                    </div>
                                    <div class="col-md-6">
                                        <label for="">Status</label>
                                        <input type="checkbox" <?= $data['status'] ? "checked":"" ?>name="status">
                                    </div>
                                    <div class="col-md-6">
                                        <label for="">Popular</label>
                                        <input type="checkbox" <?= $data['popular'] ? "checked":"" ?> name="popular">
                                    </div>
                                    <div class="col-md-12">
                                        <button type="submit" class="btn btn-primary" name="update_category_btn">
                                            Update
                                        </button>
                                    </div>
                                </div>
                            </form>
                        </div>          
                    </div>
            <?php
                }
                else 
                {
                    echo "Category not found";
                }
            ?>
            <?php } else { echo "Something went wrong"; } ?>
        </div>  
    </div>
</div>
<?php include('includes/footer.php')?>

code.php（对应更新分类逻辑段） #

else if(isset($_POST['update_category_btn']))
{
    $category_id = $_POST['category_id']; 
    $name = $_POST['name'];
    $slug = $_POST['slug'];
    $description = $_POST['description'];
    $meta_title = $_POST['meta_title'];
    $meta_description = $_POST['meta_description'];
    $meta_keywords = $_POST['meta_keywords'];
    $status = isset($_POST['status']) ? '1':'0' ;
    $popular = isset($_POST['popular']) ? '1':'0' ;

    // 上传新图片变量
    $new_image = $_FILES['image']['name'];
    // 存储旧图片名
    $old_image = $_POST['old_image'];

    // 新图片不为空则生成新文件名
    if($new_image != "")
    {
        $image_ext = pathinfo($new_image, PATHINFO_EXTENSION);
        $update_filename = time().'.'.$image_ext;
    }
    // 新图片为空则沿用旧文件名
    else
    {
        $update_filename = $old_image;
    }

    $path = "../uploads";

    $update_query = "UPDATE categories SET name='$name', slug='$slug', description='$description', meta_title='$meta_title', meta_description='$meta_description', meta_keywords='$meta_keywords', status='$status', popular='$popular', image='$update_filename' WHERE id= '$category_id' ";

    $update_query_run = mysqli_query($con, $update_query);

    if($update_query_run)
    {
        if($_FILES['image']['name'] != "")
        {
            move_uploaded_file($_FILES['image']['tmp_name'], $path.'/'.$update_filename);
            // 修复后删除旧文件逻辑
            if(file_exists("../uploads/".$old_image))
            {
                unlink("../uploads/".$old_image);
            }
        }
        redirect("edit-category.php?id=$category_id", "Category updated successfully!");
    }
    else 
    {
        redirect("edit-category.php?id=$category_id", "Update failed");     
    }
}

内容的提问来源于stack exchange，提问作者mynameiswadey