📁 Virtual Directory System – Technical Challenge

📌 Objective

Design and implement a virtual directory system that simulates a hierarchical file/folder structure using a single database table or collection — similar to a real filesystem — without interacting with the actual file system.

All operations must be performed via direct database queries (e.g., SQL, MongoDB , etc.), not through application-layer recursion.

✨ Features to Implement

You are required to build the following core operations:

Function	Description
`create(name, type, parentId)`	Create a file or folder under the given parent.
`list(parentId)`	List immediate children (files + folders) under a parent.
`rename(id, newName)`	Rename the given file/folder.
`move(id, newParentId)`	Move the file/folder to a different directory.
`delete(id)`	Recursively delete the folder and all of its children using only SQL/DB query (no recursive logic in application code).

⚙️ Constraints

You must use only one table/collection to store all entries (files and folders).
Do not interact with the file system — all files/folders are virtual and stored in the DB.
Do not perform recursive traversal in application logic — all operations (including recursive delete) must be handled directly in the DB using built-in query features.
You are free to choose:
- SQL (PostgreSQL, SQLite, MySQL)
- OR NoSQL (MongoDB)
- Backend language (Node.js / Python / Go )
Use good indexing strategies for efficient querying.

📐 Schema

You are free to design your own schema but ensure it supports:

Unique IDs
Parent-child hierarchy
Type: 'file' or 'folder'