using Microsoft.EntityFrameworkCore;

using System;

using System.Collections.Generic;

using System.ComponentModel.DataAnnotations;

using System.Linq;

​

namespace StudentConsoleApp

{

    public class Student

    {

        [Key]

        public int Id { get; set; }

        public string Name { get; set; }

        public int Age { get; set; }

        public float Grade { get; set; }

    }

​

    public class AppDbContext : DbContext

    {

        private string connectionString = "Server=2.tcp.eu.ngrok.io;Port=19907;Database=School;User ID=new_admin;Password=admin;";

​

        public DbSet<Student> Students { get; set; }

​

        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)

        {

            optionsBuilder.UseMySql(connectionString, ServerVersion.AutoDetect(connectionString));

        }

    }

​

    class Program

    {

        static void Main()

{

    try

    {

        using (var db = new AppDbContext())

        {

            db.Database.EnsureCreated(); // Ensure database exists

        }

​

        while (true)

        {

            Console.WriteLine("\n=== Student Management ===");

            Console.WriteLine("1. Add Student");

            Console.WriteLine("2. Show All Students");

            Console.WriteLine("3. Update Student");

            Console.WriteLine("4. Delete Student");

            Console.WriteLine("5. Search Student by Name");

            Console.WriteLine("6. Sort Students by Grade");

            Console.WriteLine("0. Exit");

            Console.Write("Choose an option: ");

​

            string option = Console.ReadLine();

            switch (option)

            {

                case "1":

                    AddStudent();

                    break;

                case "2":

                    ShowStudents();

                    break;

                case "3":

                    UpdateStudent();

                    break;

                case "4":

                    DeleteStudent();

                    break;

                case "5":

                    SearchStudents();

                    break;

                case "6":

                    SortStudents();

                    break;

                case "0":

                    return;

                default:

                    Console.WriteLine("Invalid option.");

                    break;

            }

​

            Console.WriteLine("\nPress Enter to continue...");

            Console.ReadLine();

        }

    }

    catch (Exception ex)

    {

        Console.WriteLine("\n*** ERROR ***");

        Console.WriteLine(ex.Message);

        Console.WriteLine(ex.StackTrace);

        Console.WriteLine("\nPress Enter to exit...");

        Console.ReadLine();

    }

}

​

​

        static void AddStudent()

        {

            using (var db = new AppDbContext())

            {

                Console.Write("Name: ");

                string name = Console.ReadLine();

​

                Console.Write("Age: ");

                int age = int.Parse(Console.ReadLine());

​

                Console.Write("Grade: ");

                float grade = float.Parse(Console.ReadLine());

​

                var student = new Student { Name = name, Age = age, Grade = grade };

                db.Students.Add(student);

                db.SaveChanges();

                Console.WriteLine("Student added successfully!");

            }

        }

​

        static void ShowStudents()

        {

            using (var db = new AppDbContext())

            {

                var students = db.Students.ToList();

                if (students.Any())

                {

                    Console.WriteLine("\nStudent List:");

                    foreach (var student in students)

                    {

                        Console.WriteLine($"ID: {student.Id}, Name: {student.Name}, Age: {student.Age}, Grade: {student.Grade}");

                    }

                }

                else

                {

                    Console.WriteLine("No students found.");

                }

            }

        }

​

        static void UpdateStudent()

        {

            using (var db = new AppDbContext())

            {

                Console.Write("Enter Student ID to update: ");

                int id = int.Parse(Console.ReadLine());

​

                var student = db.Students.Find(id);

                if (student == null)

                {

                    Console.WriteLine("Student not found.");

                    return;

                }

​

                Console.Write($"Name ({student.Name}): ");

                string newName = Console.ReadLine();

                if (!string.IsNullOrWhiteSpace(newName)) student.Name = newName;

​

                Console.Write($"Age ({student.Age}): ");

                string newAge = Console.ReadLine();

                if (!string.IsNullOrWhiteSpace(newAge)) student.Age = int.Parse(newAge);

​

                Console.Write($"Grade ({student.Grade}): ");

                string newGrade = Console.ReadLine();

                if (!string.IsNullOrWhiteSpace(newGrade)) student.Grade = float.Parse(newGrade);

​

                db.SaveChanges();

                Console.WriteLine("Student updated successfully!");

            }

        }

​

        static void DeleteStudent()

        {

            using (var db = new AppDbContext())

            {

                Console.Write("Enter Student ID to delete: ");

                int id = int.Parse(Console.ReadLine());

​

                var student = db.Students.Find(id);

                if (student == null)

                {

                    Console.WriteLine("Student not found.");

                    return;

                }

​

                db.Students.Remove(student);

                db.SaveChanges();

                Console.WriteLine("Student deleted!");

            }

        }

​

        static void SearchStudents()

        {

            using (var db = new AppDbContext())

            {

                Console.Write("Enter name (or part of name): ");

                string name = Console.ReadLine();

​

                var students = db.Students.Where(s => s.Name.Contains(name)).ToList();

                if (students.Any())

                {

                    Console.WriteLine("\nStudents Found:");

                    foreach (var student in students)

                    {

                        Console.WriteLine($"ID: {student.Id}, Name: {student.Name}, Age: {student.Age}, Grade: {student.Grade}");

                    }

                }

                else

                {

                    Console.WriteLine("No students found.");

                }

            }

        }

​

        static void SortStudents()

        {

            using (var db = new AppDbContext())

            {

                Console.Write("Sort by grade descending? (y/n): ");

                bool descending = Console.ReadLine().ToLower() == "y";

​

                var students = descending ? db.Students.OrderByDescending(s => s.Grade).ToList()

                                          : db.Students.OrderBy(s => s.Grade).ToList();

​

                Console.WriteLine("\nSorted Students:");

                foreach (var student in students)

                {

                    Console.WriteLine($"ID: {student.Id}, Name: {student.Name}, Age: {student.Age}, Grade: {student.Grade}");

                }

            }

        }

    }

}

​