# Student Management System

A terminal CRUD application for managing **Students**, **Guardians**, and
**Attendance** records, backed by MySQL. Built against the schema in
Tables 9.3–9.5 (STUDENT, GUARDIAN, ATTENDANCE).

## What it does on startup

1. Connects to the MySQL server at `10.10.0.160:3306`.
2. Verifies the `student_db` database exists — creates it if not.
3. Verifies the `GUARDIAN`, `STUDENT`, and `ATTENDANCE` tables exist
	(in that order, since STUDENT references GUARDIAN and ATTENDANCE
	references STUDENT) — creates any that are missing, with the exact
	data types and constraints from the schema (primary keys, foreign
	keys, `NOT NULL`, `UNIQUE` on `GPhone`, and the composite primary key
	`(AttendanceDate, RollNumber)` on ATTENDANCE).
4. Launches an interactive menu for Create / Read / Update / Delete.

## Setup

1. Install the one dependency:

	```bash
	pip install -r requirements.txt
	```

2. Set your MySQL credentials as environment variables (the host/port/
	database default to the assignment's values already):

	```bash
	export DB_USER=root
	export DB_PASSWORD=your_password_here
	# optional overrides — these already default correctly:
	# export DB_HOST=10.10.0.160
	# export DB_PORT=3306
	# export DB_NAME=student_db
	```

3. Run it:

	```bash
	python3 main.py
	```

## Files

| File            | Purpose                                                        |
|-----------------|------------------------------------------------------------------|
| `config.py`     | Connection settings (reads env vars, falls back to defaults)   |
| `db.py`         | Connects to MySQL; verifies/creates the database and tables    |
| `crud.py`       | All Create/Read/Update/Delete operations for the three tables  |
| `ui_helpers.py` | Input prompts/validation and table-printing for the terminal   |
| `main.py`       | The menu-driven application — run this                         |

## Using the app

The main menu has three sections:

- **Guardian management** — list, view, add, update, delete guardians.
  GUID must be a 12-digit number (per the Aadhaar-number schema note);
  phone, if given, must be 10 digits and is unique across guardians.
- **Student management** — list, view, add, update, delete students.
  Roll number is up to 3 digits; each student must reference an
  existing guardian's GUID (add the guardian first).
- **Attendance management** — mark attendance (P/A) for a student on a
  date (marking the same student+date again updates it instead of
  erroring), view attendance by date or by student, and delete records.

Deleting a guardian who still has students is blocked by the foreign
key (delete or reassign their students first). Deleting a student
cascades and removes their attendance records automatically.

## Notes

- Uses [mysql-connector-python](https://dev.mysql.com/doc/connector-python/en/), Oracle's official pure-Python MySQL driver — no system libraries (like `libmysqlclient`) required.
- All input is validated against the schema's constraints (max lengths, digit counts, date format, P/A status) before hitting the database, and database-level errors (duplicate keys, foreign key violations) are caught and shown as friendly messages rather than crashing.
- Tested end-to-end (connect → create DB/tables → full CRUD → constraint error handling → cascade delete) against a local MySQL/MariaDB instance before delivery.