using System;

using System.Collections.Generic;

using System.Linq;

using System.Threading.Tasks;

using Microsoft.EntityFrameworkCore;

using Microsoft.EntityFrameworkCore.SqlServer;

​

​

public class Product

{

    public int Id { get; set; }

    public string Name { get; set; }

    public decimal Price { get; set; }

}

​

public class AppDbContext : DbContext

{

    public DbSet<Product> Products { get; set; }

​

    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)

    {

        optionsBuilder.UseInMemoryDatabase("ProductDb");

    }

}

​

public class ProductService

{

    private readonly AppDbContext _context;

​

    public ProductService(AppDbContext context)

    {

        _context = context;

    }

​

    public async Task AddProductAsync(Product product)

    {

        _context.Products.Add(product);

        await _context.SaveChangesAsync();

    }

​

    public async Task<List<Product>> GetAllProductsAsync()

    {

        return await _context.Products.ToListAsync();

    }

​

    public async Task<Product> GetProductByIdAsync(int id)

    {

        return await _context.Products.FindAsync(id);

    }

​

    public async Task UpdateProductAsync(Product product)

    {

        _context.Products.Update(product);

        await _context.SaveChangesAsync();

    }

​

    public async Task DeleteProductAsync(int id)

    {

        var product = await _context.Products.FindAsync(id);

        if (product != null)

        {

            _context.Products.Remove(product);

            await _context.SaveChangesAsync();

        }

    }

}

​

public class Program

{

    public static async Task Main(string[] args)

    {

        using var context = new AppDbContext();

        var service = new ProductService(context);

​

        // Adding a product

        var product = new Product { Name = "Laptop", Price = 1200 };

        await service.AddProductAsync(product);

        Console.WriteLine("Product added.");

​

        // Retrieving products

        var products = await service.GetAllProductsAsync();

        Console.WriteLine("All Products:");

        foreach (var p in products)

        {

            Console.WriteLine($"{p.Id}: {p.Name} - ${p.Price}");

        }

​

        // Updating a product

        product.Price = 1100;

        await service.UpdateProductAsync(product);

        Console.WriteLine("Product updated.");

​

        // Deleting a product

        await service.DeleteProductAsync(product.Id);

        Console.WriteLine("Product deleted.");

    }

}

​