# Student Management System (MW600)

A mini system for managing student records, built with **Express** and **MySQL**.

Backend is a single file (`server.js`) exposing a CRUD API; the frontend is a
plain HTML page (`index.html`) served from the same server.

## Requirements

- Node.js 20.6+ (uses `process.loadEnvFile`)
- A running MySQL server

## Setup

```sh
npm install
cp .env.example .env      # then fill in your MySQL credentials
npm run db:push           # creates the database and imports student_db.sql
npm start
```

Open http://localhost:3000

`npm run db:push` creates the `student_db` database and imports the schema and
seed data from `student_db.sql`. It is safe to re-run — the script drops and
recreates the `students` table.

## Database

`student_db.sql` holds the schema and seed rows for a single table:

| Column       | Type         | Notes                        |
| ------------ | ------------ | ---------------------------- |
| `id`         | `INT`        | Primary key, assigned by app |
| `name`       | `VARCHAR(100)` | Required                   |
| `course`     | `VARCHAR(50)`  | Required                   |
| `year_level` | `INT`        | Required, 1–6              |

### ID format

Ids are **8 digits**: a 2-digit year followed by a 6-digit counter that resets
each year.

```
26 000001   -> first student added in 2026
26 000002   -> second student added in 2026
27 000001   -> first student added in 2027
```

The counter is per year, so ids never collide across years. Because MySQL cannot
generate this pattern, `id` has no `AUTO_INCREMENT` — the application assigns it.
Allocation is guarded by a MySQL advisory lock (`GET_LOCK`) so simultaneous
requests cannot receive the same id.

## API

| Method   | Path                 | Response                                     |
| -------- | -------------------- | -------------------------------------------- |
| `GET`    | `/api/students`      | `200` list of students                       |
| `GET`    | `/api/students/:id`  | `200` student, `400` bad id, `404` not found |
| `POST`   | `/api/students`      | `201` created, `400` invalid, `415` not JSON |
| `PUT`    | `/api/students/:id`  | `200` updated, `400` invalid, `404` not found |
| `DELETE` | `/api/students/:id`  | `204` deleted, `404` not found               |

Errors use one envelope:

```json
{ "error": { "code": "VALIDATION_ERROR", "message": "...", "details": [] } }
```

## Configuration

All connection settings live in `.env` (not committed):

| Variable      | Default       |
| ------------- | ------------- |
| `DB_HOST`     | `127.0.0.1`   |
| `DB_PORT`     | `3306`        |
| `DB_USER`     | `root`        |
| `DB_PASSWORD` | *required*    |
| `DB_NAME`     | `student_db`  |
| `PORT`        | `3000`        |