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.

config.py

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+"""
+Configuration for the Student Management System.
+
+Connection settings are read from environment variables first, falling back
+to the defaults below (which match the assignment's requirements). This
+means you can run the app as-is, or override any value like:
+
+    DB_HOST=10.0.1.40 DB_USER=root DB_PASSWORD=secret python3 main.py
+"""
+
+import os
+
+DB_HOST = os.environ.get("DB_HOST", "10.0.1.40")
+DB_PORT = int(os.environ.get("DB_PORT", "3306"))
+DB_USER = os.environ.get("DB_USER", "root")
+DB_PASSWORD = os.environ.get("DB_PASSWORD", "")
+DB_NAME = os.environ.get("DB_NAME", "student_db")
+DB_CONNECT_TIMEOUT = int(os.environ.get("DB_CONNECT_TIMEOUT", "10"))

crud.py

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+"""
+CRUD operations for GUARDIAN, STUDENT and ATTENDANCE.
+
+Every function takes an open pymysql connection as its first argument and
+manages its own commit/rollback. All functions return plain data
+(dicts/lists/bool) so this module has no dependency on the UI layer.
+"""
+
+import pymysql
+
+
+class CrudError(Exception):
+	"""Raised for expected, user-facing data errors (bad FK, duplicate key, etc)."""
+	pass
+
+
+def _run(conn, sql, params=None, fetch=None):
+	"""
+	Helper: execute a statement, commit, and optionally fetch results.
+	fetch: None (no fetch), 'one', or 'all'
+	Translates common MySQL errors into CrudError with a friendly message.
+	"""
+	try:
+		with conn.cursor() as cur:
+			cur.execute(sql, params or ())
+			result = None
+			if fetch == "one":
+				result = cur.fetchone()
+			elif fetch == "all":
+				result = cur.fetchall()
+			conn.commit()
+			return result if fetch else cur.rowcount
+	except pymysql.err.IntegrityError as e:
+		conn.rollback()
+		code = e.args[0] if e.args else None
+		if code == 1062:
+			raise CrudError("A record with that primary/unique key already exists.")
+		if code in (1451, 1452):
+			raise CrudError(
+				"That operation violates a foreign key constraint "
+				"(referenced record missing, or still referenced by other rows)."
+			)
+		raise CrudError(f"Database integrity error: {e}")
+	except pymysql.err.DataError as e:
+		conn.rollback()
+		raise CrudError(f"Invalid data for one or more fields: {e}")
+	except pymysql.err.MySQLError as e:
+		conn.rollback()
+		raise CrudError(f"Database error: {e}")
+
+
+# ---------------------------------------------------------------- GUARDIAN --
+
+def create_guardian(conn, guid, gname, gphone, gaddress):
+	_run(
+		conn,
+		"INSERT INTO GUARDIAN (GUID, GName, GPhone, GAddress) VALUES (%s, %s, %s, %s)",
+		(guid, gname, gphone, gaddress),
+	)
+
+
+def get_guardian(conn, guid):
+	return _run(conn, "SELECT * FROM GUARDIAN WHERE GUID = %s", (guid,), fetch="one")
+
+
+def list_guardians(conn):
+	return _run(conn, "SELECT * FROM GUARDIAN ORDER BY GUID", fetch="all")
+
+
+def update_guardian(conn, guid, gname=None, gphone=None, gaddress=None):
+	fields, params = [], []
+	if gname is not None:
+		fields.append("GName = %s")
+		params.append(gname)
+	if gphone is not None:
+		fields.append("GPhone = %s")
+		params.append(gphone)
+	if gaddress is not None:
+		fields.append("GAddress = %s")
+		params.append(gaddress)
+	if not fields:
+		return 0
+	params.append(guid)
+	return _run(conn, f"UPDATE GUARDIAN SET {', '.join(fields)} WHERE GUID = %s", params)
+
+
+def delete_guardian(conn, guid):
+	return _run(conn, "DELETE FROM GUARDIAN WHERE GUID = %s", (guid,))
+
+
+# ----------------------------------------------------------------- STUDENT --
+
+def create_student(conn, roll_number, sname, sdateofbirth, guid):
+	_run(
+		conn,
+		"INSERT INTO STUDENT (RollNumber, SName, SDateofBirth, GUID) VALUES (%s, %s, %s, %s)",
+		(roll_number, sname, sdateofbirth, guid),
+	)
+
+
+def get_student(conn, roll_number):
+	return _run(conn, "SELECT * FROM STUDENT WHERE RollNumber = %s", (roll_number,), fetch="one")
+
+
+def list_students(conn):
+	return _run(
+		conn,
+		"""
+		SELECT s.RollNumber, s.SName, s.SDateofBirth, s.GUID, g.GName AS GuardianName
+		FROM STUDENT s
+		LEFT JOIN GUARDIAN g ON s.GUID = g.GUID
+		ORDER BY s.RollNumber
+		""",
+		fetch="all",
+	)
+
+
+def update_student(conn, roll_number, sname=None, sdateofbirth=None, guid=None):
+	fields, params = [], []
+	if sname is not None:
+		fields.append("SName = %s")
+		params.append(sname)
+	if sdateofbirth is not None:
+		fields.append("SDateofBirth = %s")
+		params.append(sdateofbirth)
+	if guid is not None:
+		fields.append("GUID = %s")
+		params.append(guid)
+	if not fields:
+		return 0
+	params.append(roll_number)
+	return _run(conn, f"UPDATE STUDENT SET {', '.join(fields)} WHERE RollNumber = %s", params)
+
+
+def delete_student(conn, roll_number):
+	return _run(conn, "DELETE FROM STUDENT WHERE RollNumber = %s", (roll_number,))
+
+
+# --------------------------------------------------------------- ATTENDANCE --
+
+def mark_attendance(conn, attendance_date, roll_number, status):
+	"""Insert attendance; if a record for that date+student exists, update it instead."""
+	existing = _run(
+		conn,
+		"SELECT 1 FROM ATTENDANCE WHERE AttendanceDate = %s AND RollNumber = %s",
+		(attendance_date, roll_number),
+		fetch="one",
+	)
+	if existing:
+		_run(
+			conn,
+			"UPDATE ATTENDANCE SET AttendanceStatus = %s "
+			"WHERE AttendanceDate = %s AND RollNumber = %s",
+			(status, attendance_date, roll_number),
+		)
+		return "updated"
+	else:
+		_run(
+			conn,
+			"INSERT INTO ATTENDANCE (AttendanceDate, RollNumber, AttendanceStatus) "
+			"VALUES (%s, %s, %s)",
+			(attendance_date, roll_number, status),
+		)
+		return "created"
+
+
+def get_attendance(conn, attendance_date, roll_number):
+	return _run(
+		conn,
+		"SELECT * FROM ATTENDANCE WHERE AttendanceDate = %s AND RollNumber = %s",
+		(attendance_date, roll_number),
+		fetch="one",
+	)
+
+
+def list_attendance_by_date(conn, attendance_date):
+	return _run(
+		conn,
+		"""
+		SELECT a.AttendanceDate, a.RollNumber, s.SName, a.AttendanceStatus
+		FROM ATTENDANCE a
+		JOIN STUDENT s ON a.RollNumber = s.RollNumber
+		WHERE a.AttendanceDate = %s
+		ORDER BY a.RollNumber
+		""",
+		(attendance_date,),
+		fetch="all",
+	)
+
+
+def list_attendance_by_student(conn, roll_number):
+	return _run(
+		conn,
+		"SELECT * FROM ATTENDANCE WHERE RollNumber = %s ORDER BY AttendanceDate",
+		(roll_number,),
+		fetch="all",
+	)
+
+
+def delete_attendance(conn, attendance_date, roll_number):
+	return _run(
+		conn,
+		"DELETE FROM ATTENDANCE WHERE AttendanceDate = %s AND RollNumber = %s",
+		(attendance_date, roll_number),
+	)

db.py

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+"""
+Database layer: connect to MySQL, verify/create the student_db database,
+and verify/create the STUDENT, GUARDIAN and ATTENDANCE tables per the
+schema (Tables 9.3, 9.4, 9.5).
+
+Schema notes:
+- GUARDIAN.GUID is the primary key (12-digit Aadhaar number, stored as CHAR(12)).
+- STUDENT.GUID is a foreign key referencing GUARDIAN.GUID.
+- ATTENDANCE has a composite primary key (AttendanceDate, RollNumber), and
+  RollNumber is also a foreign key referencing STUDENT.RollNumber.
+- Because STUDENT references GUARDIAN, GUARDIAN must be created first.
+"""
+
+import sys
+
+import pymysql
+import pymysql.cursors
+
+import config
+
+# Table creation statements, in dependency order (GUARDIAN -> STUDENT -> ATTENDANCE)
+TABLE_DEFINITIONS = {
+	"GUARDIAN": """
+		CREATE TABLE GUARDIAN (
+			GUID    CHAR(12)    NOT NULL,
+			GName   VARCHAR(20) NOT NULL,
+			GPhone  CHAR(10)    NULL,
+			GAddress VARCHAR(30) NOT NULL,
+			PRIMARY KEY (GUID),
+			UNIQUE (GPhone)
+		) ENGINE=InnoDB
+	""",
+	"STUDENT": """
+		CREATE TABLE STUDENT (
+			RollNumber   INT         NOT NULL,
+			SName        VARCHAR(20) NOT NULL,
+			SDateofBirth DATE        NOT NULL,
+			GUID         CHAR(12)    NOT NULL,
+			PRIMARY KEY (RollNumber),
+			FOREIGN KEY (GUID) REFERENCES GUARDIAN(GUID)
+				ON DELETE RESTRICT ON UPDATE CASCADE
+		) ENGINE=InnoDB
+	""",
+	"ATTENDANCE": """
+		CREATE TABLE ATTENDANCE (
+			AttendanceDate   DATE     NOT NULL,
+			RollNumber       INT      NOT NULL,
+			AttendanceStatus CHAR(1)  NOT NULL,
+			PRIMARY KEY (AttendanceDate, RollNumber),
+			FOREIGN KEY (RollNumber) REFERENCES STUDENT(RollNumber)
+				ON DELETE CASCADE ON UPDATE CASCADE,
+			CONSTRAINT chk_attendance_status CHECK (AttendanceStatus IN ('P', 'A'))
+		) ENGINE=InnoDB
+	""",
+}
+
+# Creation order matters because of foreign keys.
+TABLE_ORDER = ["GUARDIAN", "STUDENT", "ATTENDANCE"]
+
+
+def connect_server(database=None):
+	"""Connect to the MySQL server (optionally selecting a database)."""
+	try:
+		conn = pymysql.connect(
+			host=config.DB_HOST,
+			port=config.DB_PORT,
+			user=config.DB_USER,
+			password=config.DB_PASSWORD,
+			database=database,
+			connect_timeout=config.DB_CONNECT_TIMEOUT,
+			cursorclass=pymysql.cursors.DictCursor,
+			autocommit=False,
+		)
+		return conn
+	except pymysql.err.OperationalError as e:
+		print(f"\n[ERROR] Could not connect to MySQL server at "
+			  f"{config.DB_HOST}:{config.DB_PORT} as user '{config.DB_USER}'.")
+		print(f"        Details: {e}")
+		sys.exit(1)
+
+
+def ensure_database():
+	"""Verify the student_db database exists; create it if it does not."""
+	conn = connect_server(database=None)
+	try:
+		with conn.cursor() as cur:
+			cur.execute("SHOW DATABASES LIKE %s", (config.DB_NAME,))
+			exists = cur.fetchone() is not None
+			if exists:
+				print(f"[OK] Database '{config.DB_NAME}' found.")
+			else:
+				print(f"[..] Database '{config.DB_NAME}' not found. Creating it...")
+				cur.execute(
+					f"CREATE DATABASE `{config.DB_NAME}` "
+					"CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci"
+				)
+				conn.commit()
+				print(f"[OK] Database '{config.DB_NAME}' created.")
+	finally:
+		conn.close()
+
+
+def ensure_tables(conn):
+	"""Verify each required table exists; create any that are missing."""
+	with conn.cursor() as cur:
+		cur.execute("SHOW TABLES")
+		existing = {row[f"Tables_in_{config.DB_NAME}"] for row in cur.fetchall()}
+
+	for table in TABLE_ORDER:
+		if table in existing:
+			print(f"[OK] Table '{table}' found.")
+		else:
+			print(f"[..] Table '{table}' not found. Creating it...")
+			with conn.cursor() as cur:
+				cur.execute(TABLE_DEFINITIONS[table])
+			conn.commit()
+			print(f"[OK] Table '{table}' created.")
+
+
+def get_connection():
+	"""
+	Full startup sequence:
+	1. Ensure the student_db database exists (creating it if needed).
+	2. Connect to student_db.
+	3. Ensure all required tables exist (creating any that are missing).
+	Returns an open connection to student_db, ready for use.
+	"""
+	print(f"Connecting to MySQL server at {config.DB_HOST}:{config.DB_PORT} ...")
+	ensure_database()
+
+	conn = connect_server(database=config.DB_NAME)
+	print(f"[OK] Connected to database '{config.DB_NAME}'.")
+
+	ensure_tables(conn)
+	return conn

main.py

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+#!/usr/bin/env python3
+"""
+Student Management System
+==========================
+Terminal CRUD application for STUDENT / GUARDIAN / ATTENDANCE, backed by
+MySQL on 10.0.1.40:3306 (student_db).
+
+On startup this:
+  1. Connects to the MySQL server.
+  2. Verifies (or creates) the student_db database.
+  3. Verifies (or creates) the STUDENT, GUARDIAN and ATTENDANCE tables.
+  4. Launches an interactive terminal menu for CRUD operations.
+
+Run:
+	python3 main.py
+"""
+
+import sys
+
+import pymysql
+
+import crud
+import db
+from ui_helpers import (
+	clear_hint,
+	pause,
+	print_table,
+	prompt_attendance_status,
+	prompt_date,
+	prompt_guid,
+	prompt_int,
+	prompt_phone,
+	prompt_str,
+)
+
+
+# ============================================================ GUARDIAN UI ==
+
+def menu_guardians(conn):
+	while True:
+		clear_hint()
+		print("GUARDIAN MANAGEMENT")
+		print("  1. List all guardians")
+		print("  2. View a guardian")
+		print("  3. Add a guardian")
+		print("  4. Update a guardian")
+		print("  5. Delete a guardian")
+		print("  0. Back to main menu")
+		choice = input("\nChoice: ").strip()
+
+		try:
+			if choice == "1":
+				print()
+				print_table(crud.list_guardians(conn))
+				pause()
+			elif choice == "2":
+				guid = prompt_guid()
+				row = crud.get_guardian(conn, guid)
+				print()
+				print_table([row] if row else [])
+				pause()
+			elif choice == "3":
+				add_guardian(conn)
+			elif choice == "4":
+				update_guardian(conn)
+			elif choice == "5":
+				delete_guardian(conn)
+			elif choice == "0":
+				return
+			else:
+				print("  Invalid choice.")
+		except crud.CrudError as e:
+			print(f"\n  [ERROR] {e}")
+			pause()
+
+
+def add_guardian(conn):
+	print("\n-- Add Guardian --")
+	guid = prompt_guid()
+	gname = prompt_str("Guardian name", max_len=20)
+	gphone = prompt_phone()
+	gaddress = prompt_str("Guardian address", max_len=30)
+	crud.create_guardian(conn, guid, gname, gphone, gaddress)
+	print(f"  [OK] Guardian {guid} added.")
+	pause()
+
+
+def update_guardian(conn):
+	print("\n-- Update Guardian --")
+	guid = prompt_guid()
+	existing = crud.get_guardian(conn, guid)
+	if not existing:
+		print("  No guardian found with that GUID.")
+		pause()
+		return
+	print(f"  Current: {existing}")
+	print("  (Press Enter to leave a field unchanged)")
+	gname = prompt_str("New name", max_len=20, allow_blank_skip=True)
+	gphone_raw = input("New phone (10 digits, blank = unchanged, 'clear' = remove): ").strip()
+	gphone = existing["GPhone"]
+	if gphone_raw.lower() == "clear":
+		gphone = None
+	elif gphone_raw:
+		gphone = prompt_phone_validate(gphone_raw)
+		if gphone is None:
+			print("  Invalid phone — update aborted for that field.")
+			gphone = existing["GPhone"]
+	gaddress = prompt_str("New address", max_len=30, allow_blank_skip=True)
+
+	crud.update_guardian(conn, guid, gname=gname, gphone=gphone, gaddress=gaddress)
+	print("  [OK] Guardian updated.")
+	pause()
+
+
+def prompt_phone_validate(raw):
+	import re
+	return raw if re.match(r"^\d{10}$", raw) else None
+
+
+def delete_guardian(conn):
+	print("\n-- Delete Guardian --")
+	guid = prompt_guid()
+	confirm = input(f"  Type 'yes' to confirm deleting guardian {guid}: ").strip().lower()
+	if confirm != "yes":
+		print("  Cancelled.")
+		pause()
+		return
+	rows = crud.delete_guardian(conn, guid)
+	if rows:
+		print("  [OK] Guardian deleted.")
+	else:
+		print("  No guardian found with that GUID.")
+	pause()
+
+
+# ============================================================= STUDENT UI ==
+
+def menu_students(conn):
+	while True:
+		clear_hint()
+		print("STUDENT MANAGEMENT")
+		print("  1. List all students")
+		print("  2. View a student")
+		print("  3. Add a student")
+		print("  4. Update a student")
+		print("  5. Delete a student")
+		print("  0. Back to main menu")
+		choice = input("\nChoice: ").strip()
+
+		try:
+			if choice == "1":
+				print()
+				print_table(crud.list_students(conn))
+				pause()
+			elif choice == "2":
+				roll = prompt_int("Roll number", max_digits=3)
+				row = crud.get_student(conn, roll)
+				print()
+				print_table([row] if row else [])
+				pause()
+			elif choice == "3":
+				add_student(conn)
+			elif choice == "4":
+				update_student(conn)
+			elif choice == "5":
+				delete_student(conn)
+			elif choice == "0":
+				return
+			else:
+				print("  Invalid choice.")
+		except crud.CrudError as e:
+			print(f"\n  [ERROR] {e}")
+			pause()
+
+
+def add_student(conn):
+	print("\n-- Add Student --")
+	roll = prompt_int("Roll number (max 3 digits)", max_digits=3)
+	sname = prompt_str("Student name", max_len=20)
+	dob = prompt_date("Date of birth")
+	print("  (Guardian must already exist — add them first via Guardian Management if needed)")
+	guid = prompt_guid()
+	crud.create_student(conn, roll, sname, dob, guid)
+	print(f"  [OK] Student {roll} added.")
+	pause()
+
+
+def update_student(conn):
+	print("\n-- Update Student --")
+	roll = prompt_int("Roll number", max_digits=3)
+	existing = crud.get_student(conn, roll)
+	if not existing:
+		print("  No student found with that roll number.")
+		pause()
+		return
+	print(f"  Current: {existing}")
+	print("  (Press Enter to leave a field unchanged)")
+	sname = prompt_str("New name", max_len=20, allow_blank_skip=True)
+	dob = prompt_date("New date of birth", allow_blank_skip=True)
+	guid = prompt_guid("New guardian GUID", allow_blank_skip=True)
+
+	crud.update_student(conn, roll, sname=sname, sdateofbirth=dob, guid=guid)
+	print("  [OK] Student updated.")
+	pause()
+
+
+def delete_student(conn):
+	print("\n-- Delete Student --")
+	roll = prompt_int("Roll number", max_digits=3)
+	confirm = input(f"  Type 'yes' to confirm deleting student {roll} "
+					 f"(also deletes their attendance records): ").strip().lower()
+	if confirm != "yes":
+		print("  Cancelled.")
+		pause()
+		return
+	rows = crud.delete_student(conn, roll)
+	if rows:
+		print("  [OK] Student deleted.")
+	else:
+		print("  No student found with that roll number.")
+	pause()
+
+
+# =========================================================== ATTENDANCE UI ==
+
+def menu_attendance(conn):
+	while True:
+		clear_hint()
+		print("ATTENDANCE MANAGEMENT")
+		print("  1. Mark / update attendance for a student")
+		print("  2. View attendance by date")
+		print("  3. View attendance history for a student")
+		print("  4. Delete an attendance record")
+		print("  0. Back to main menu")
+		choice = input("\nChoice: ").strip()
+
+		try:
+			if choice == "1":
+				mark_attendance(conn)
+			elif choice == "2":
+				d = prompt_date("Date")
+				print()
+				print_table(crud.list_attendance_by_date(conn, d))
+				pause()
+			elif choice == "3":
+				roll = prompt_int("Roll number", max_digits=3)
+				print()
+				print_table(crud.list_attendance_by_student(conn, roll))
+				pause()
+			elif choice == "4":
+				delete_attendance(conn)
+			elif choice == "0":
+				return
+			else:
+				print("  Invalid choice.")
+		except crud.CrudError as e:
+			print(f"\n  [ERROR] {e}")
+			pause()
+
+
+def mark_attendance(conn):
+	print("\n-- Mark Attendance --")
+	roll = prompt_int("Roll number", max_digits=3)
+	if not crud.get_student(conn, roll):
+		print("  No student found with that roll number.")
+		pause()
+		return
+	d = prompt_date("Date")
+	status = prompt_attendance_status()
+	result = crud.mark_attendance(conn, d, roll, status)
+	print(f"  [OK] Attendance {result} for student {roll} on {d}: {status}")
+	pause()
+
+
+def delete_attendance(conn):
+	print("\n-- Delete Attendance Record --")
+	roll = prompt_int("Roll number", max_digits=3)
+	d = prompt_date("Date")
+	confirm = input("  Type 'yes' to confirm: ").strip().lower()
+	if confirm != "yes":
+		print("  Cancelled.")
+		pause()
+		return
+	rows = crud.delete_attendance(conn, d, roll)
+	if rows:
+		print("  [OK] Attendance record deleted.")
+	else:
+		print("  No matching attendance record found.")
+	pause()
+
+
+# ================================================================ MAIN ====
+
+def main_menu(conn):
+	while True:
+		clear_hint()
+		print("STUDENT MANAGEMENT SYSTEM")
+		print("  1. Guardian management")
+		print("  2. Student management")
+		print("  3. Attendance management")
+		print("  0. Exit")
+		choice = input("\nChoice: ").strip()
+
+		if choice == "1":
+			menu_guardians(conn)
+		elif choice == "2":
+			menu_students(conn)
+		elif choice == "3":
+			menu_attendance(conn)
+		elif choice == "0":
+			print("\nGoodbye!")
+			return
+		else:
+			print("  Invalid choice.")
+
+
+def main():
+	print("=" * 60)
+	print(" STUDENT MANAGEMENT SYSTEM - Startup")
+	print("=" * 60)
+
+	conn = db.get_connection()
+
+	print("\nAll checks passed. Starting application...\n")
+	try:
+		main_menu(conn)
+	except KeyboardInterrupt:
+		print("\n\nInterrupted. Exiting.")
+	except pymysql.err.MySQLError as e:
+		print(f"\n[ERROR] Lost database connection: {e}")
+		sys.exit(1)
+	finally:
+		conn.close()
+
+
+if __name__ == "__main__":
+	main()

requirements.txt

@@ -0,0 +1 @@
+PyMySQL>=1.1.0

ui_helpers.py

@@ -0,0 +1,118 @@
+"""Small input-prompting and formatting helpers shared by the menu screens."""
+
+import datetime
+import re
+
+GUID_RE = re.compile(r"^\d{12}$")
+PHONE_RE = re.compile(r"^\d{10}$")
+
+
+def pause():
+	input("\nPress Enter to continue...")
+
+
+def clear_hint():
+	print("\n" + "-" * 60 + "\n")
+
+
+def prompt_str(label, max_len=None, required=True, allow_blank_skip=False):
+	"""Prompt for a string. allow_blank_skip=True returns None on empty input (for 'leave unchanged')."""
+	while True:
+		suffix = f" (max {max_len} chars)" if max_len else ""
+		val = input(f"{label}{suffix}: ").strip()
+		if not val:
+			if allow_blank_skip:
+				return None
+			if required:
+				print("  This field is required.")
+				continue
+			return ""
+		if max_len and len(val) > max_len:
+			print(f"  Too long — max {max_len} characters.")
+			continue
+		return val
+
+
+def prompt_int(label, max_digits=None, allow_blank_skip=False):
+	while True:
+		val = input(f"{label}: ").strip()
+		if not val:
+			if allow_blank_skip:
+				return None
+			print("  This field is required.")
+			continue
+		if not val.isdigit():
+			print("  Please enter a whole number.")
+			continue
+		if max_digits and len(val) > max_digits:
+			print(f"  Too many digits — max {max_digits}.")
+			continue
+		return int(val)
+
+
+def prompt_guid(label="Guardian ID / GUID (12-digit Aadhaar number)", allow_blank_skip=False):
+	while True:
+		val = input(f"{label}: ").strip()
+		if not val:
+			if allow_blank_skip:
+				return None
+			print("  This field is required.")
+			continue
+		if not GUID_RE.match(val):
+			print("  GUID must be exactly 12 digits.")
+			continue
+		return val
+
+
+def prompt_phone(label="Guardian phone (10 digits, optional)", allow_blank_skip=True):
+	while True:
+		val = input(f"{label}: ").strip()
+		if not val:
+			return None  # NULL is allowed for GPhone
+		if not PHONE_RE.match(val):
+			print("  Phone must be exactly 10 digits (or leave blank).")
+			continue
+		return val
+
+
+def prompt_date(label, allow_blank_skip=False):
+	while True:
+		val = input(f"{label} (YYYY-MM-DD): ").strip()
+		if not val:
+			if allow_blank_skip:
+				return None
+			print("  This field is required.")
+			continue
+		try:
+			return datetime.datetime.strptime(val, "%Y-%m-%d").date()
+		except ValueError:
+			print("  Invalid date — use format YYYY-MM-DD, e.g. 2015-08-21.")
+
+
+def prompt_attendance_status(label="Status (P=present, A=absent)"):
+	while True:
+		val = input(f"{label}: ").strip().upper()
+		if val in ("P", "A"):
+			return val
+		print("  Please enter 'P' or 'A'.")
+
+
+def print_table(rows, columns=None):
+	"""Pretty-print a list of dict rows as a simple aligned table."""
+	if not rows:
+		print("  (no records found)")
+		return
+
+	if columns is None:
+		columns = list(rows[0].keys())
+
+	widths = {}
+	for col in columns:
+		widths[col] = max(len(str(col)), *(len(str(r.get(col, ""))) for r in rows))
+
+	header = "  " + " | ".join(str(col).ljust(widths[col]) for col in columns)
+	print(header)
+	print("  " + "-+-".join("-" * widths[col] for col in columns))
+	for r in rows:
+		print("  " + " | ".join(str(r.get(col, "")).ljust(widths[col]) for col in columns))
+	print(f"\n  ({len(rows)} record{'s' if len(rows) != 1 else ''})")