无法将图像上传到数据库

Question

我有一个问题，我无法将图像从表单上传到数据库。问题是我无法获取图像的路径和图像名称。结果，它不会通过if语句，也不会上传到数据库。任何帮助将不胜感激。

  <form action="<?php echo htmlspecialchars('register_parse.php');?>" method='post'>
          <div class="avatar"><label>Upload a picture: </label><input type="file" name="avatar" accept="image/*" required></div>
  </form>

这是register_parse.php文件：

  if(isset($_POST['email']) && isset($_POST['avatar'])){

            $avatar_path = $mysqli->real_escape_string('img/'.$FILES['avatar']['name']);

            // Check if user with that email already exists
            $result = $mysqli->query("SELECT * FROM users WHERE email='$email'") or die($mysqli->error());

            // We know user email exists if the rows returned are more than 0
            if ( $result->num_rows > 0 ) {
                $_SESSION['message'] = 'User with this email already exists!';
                header("location: error.php");   
        }

        else{
            if(preg_match("!image!",$_FILES['avatar']['type'])){

                if(copy($_FILES['avatar']['tmp_name'], $avatar_path)){
                        $_SESSION['avatar']=$avatar_path;


        $sql = "INSERT INTO users (email, image) VALUES ('".$email."','".$avatar_path."')";

        $res = mysqli_query($mysqli, $sql) or die(mysqli_error($mysqli));

        if($mysqli->query($sql) === true){
                $_SESSION['message'] = "Registration successful.";
                header("location: success.php");
  }
                    }
                    else{
                            $_SESSION['message'] = "User could not be added to the database.";
                            header("location: error.php");                              
                        }
            }
            else{
                    $_SESSION['message'] = "File upload failed";
                    header("location: error.php");                  
                }       
    }
}

  }
  ?>

它总是转到FILE Upload Failed。当我删除最后两个if语句if（preg_match（“！image！”，$ _ FILES ['avatar'] ['type']））和if（copy（$ _ FILES ['avatar'] ['tmp_name']时， $ avatar_path）），一切正常，但是在数据库中，我得到图像的路径只是img /，因此它无法获得图像的路径。