def add_student():
    roll_no = int(input("Enter Roll Number: "))
    name = input("Enter Name: ").strip()
    class_name = input("Enter Class: ").strip()
    age = int(input("Enter Age: "))
    phone = input("Enter Phone Number: ").strip()

    conn = connect_db()
    cur = conn.cursor()
    cur.execute(
        "INSERT INTO students (roll_no, name, class_name, age, phone) VALUES (?, ?, ?, ?, ?)",
        (roll_no, name, class_name, age, phone)
    )
    conn.commit()

def view_students():
    cur.execute("SELECT * FROM students ORDER BY roll_no")
    rows = cur.fetchall()

    for r in rows:
        print(f"{r[0]:<10}{r[1]:<20}{r[2]:<10}{r[3]:<6}{r[4]:<15}")

def search_student():
    cur.execute("SELECT * FROM students WHERE roll_no = ?", (roll_no,))
    row = cur.fetchone()

def update_student():
    cur.execute("SELECT * FROM students WHERE roll_no = ?", (roll_no,))
    row = cur.fetchone()

    name = input(f"Name [{row[1]}]: ").strip() or row[1]
    ...
    cur.execute(
        "UPDATE students SET name=?, class_name=?, age=?, phone=? WHERE roll_no=?",
        (name, class_name, age, phone, roll_no)
    )

def delete_student():
    confirm = input(f"Are you sure you want to delete '{row[1]}'? (y/n): ").lower()
    if confirm == "y":
        cur.execute("DELETE FROM students WHERE roll_no = ?", (roll_no,))
        cur.execute("DELETE FROM attendance WHERE roll_no = ?", (roll_no,))
        cur.execute("DELETE FROM grades WHERE roll_no = ?", (roll_no,))