php上传图片并将文件名保存到mysql

<form action="upload.php" method="post" enctype="multipart/form-data">
  <input type="file" name="image">
  <input type="submit" value="上传">
</form>

<?php
$servername = "数据库服务器地址";
$username = "数据库用户名";
$password = "数据库密码";
$dbname = "数据库名";

$conn = new mysqli($servername, $username, $password, $dbname);
if ($conn->connect_error) {
    die("连接失败: " . $conn->connect_error);
}
?>

<?php
if(isset($_FILES['image'])){
    $file_name = $_FILES['image']['name'];
    $file_tmp = $_FILES['image']['tmp_name'];
    $file_type = $_FILES['image']['type'];
    $file_size = $_FILES['image']['size'];
    
    // 检查文件是否为图片类型
    $allowed_extensions = array("jpg", "jpeg", "png");
    $file_extension = pathinfo($file_name, PATHINFO_EXTENSION);
    if(!in_array($file_extension, $allowed_extensions)){
        echo "只允许上传jpg、jpeg和png格式的图片.";
    } elseif($file_size > 2097152){
        echo "图片大小不能超过2MB.";
    } else {
        // 将文件从临时位置移动到目标位置
        $target_path = "uploads/" . $file_name;
        if(move_uploaded_file($file_tmp, $target_path)){
            // 将文件名保存到MySQL数据库
            $sql = "INSERT INTO images (file_name) VALUES ('$file_name')";
            if($conn->query($sql) === TRUE){
                echo "文件上传成功，并已保存到数据库.";
            } else {
                echo "保存文件名到数据库时出错: " . $conn->error;
            }
        } else {
            echo "文件上传失败.";
        }
    }
}
?>

<?php
$conn->close();
?>