project-init

README.md

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+# 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 `10.0.1.40:3306`.
+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=10.0.1.40
+   # 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 [PyMySQL](https://pymysql.readthedocs.io/), a pure-Python MySQL
+  client — 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.