I want .net code with all crud operations and export excel also

example with crud 

using System;
using System.Collections.Generic;
using System.Data;
using System.Linq;
using System.IO;
using OfficeOpenXml; // Install EPPlus NuGet package

// Example Entity (replace with your actual entity)
public class Product
{
    public int Id { get; set; }
    public string Name { get; set; }
    public decimal Price { get; set; }
    public int Quantity { get; set; }
}

public class ProductManager
{
    private List products; // In-memory list for demonstration. Replace with database access.

    public ProductManager()
    {
        products = new List();
        // Initialize with some sample data (replace with your data loading logic)
        products.Add(new Product { Id = 1, Name = "Laptop", Price = 1200, Quantity = 10 });
        products.Add(new Product { Id = 2, Name = "Mouse", Price = 25, Quantity = 50 });
    }

    // Create
    public void AddProduct(Product product)
    {
        product.Id = products.Count + 1; // Simple ID generation for demo
        products.Add(product);
    }

    // Read (All)
    public List GetAllProducts()
    {
        return products;
    }

    // Read (Single)
    public Product GetProductById(int id)
    {
        return products.FirstOrDefault(p => p.Id == id);
    }

    // Update
    public void UpdateProduct(Product product)
    {
        var existingProduct = products.FirstOrDefault(p => p.Id == product.Id);
        if (existingProduct != null)
        {
            existingProduct.Name = product.Name;
            existingProduct.Price = product.Price;
            existingProduct.Quantity = product.Quantity;
        }
    }

    // Delete
    public void DeleteProduct(int id)
    {
        var productToRemove = products.FirstOrDefault(p => p.Id == id);
        if (productToRemove != null)
        {
            products.Remove(productToRemove);
        }
    }

    // Export to Excel
    public void ExportToExcel(string filePath)
    {
        using (var package = new ExcelPackage())
        {
            var worksheet = package.Workbook.Worksheets.Add("Products");

            // Add header row
            worksheet.Cells[1, 1].Value = "Id";
            worksheet.Cells[1, 2].Value = "Name";
            worksheet.Cells[1, 3].Value = "Price";
            worksheet.Cells[1, 4].Value = "Quantity";

            // Add data rows
            for (int i = 0; i < products.Count; i++)
            {
                worksheet.Cells[i + 2, 1].Value = products[i].Id;
                worksheet.Cells[i + 2, 2].Value = products[i].Name;
                worksheet.Cells[i + 2, 3].Value = products[i].Price;
                worksheet.Cells[i + 2, 4].Value = products[i].Quantity;
            }

            package.SaveAs(new FileInfo(filePath));
        }
    }
}

class Program
{
    static void Main(string[] args)
    {
        var productManager = new ProductManager();

        // Example usage:
        // Create
        productManager.AddProduct(new Product { Name = "Keyboard", Price = 75, Quantity = 20 });

        // Read
        var allProducts = productManager.GetAllProducts();
        foreach (var product in allProducts)
        {
            Console.WriteLine($"Id: {product.Id}, Name: {product.Name}, Price: {product.Price}, Quantity: {product.Quantity}");
        }

        // Update
        var productToUpdate = productManager.GetProductById(2);
        if (productToUpdate != null)
        {
            productToUpdate.Price = 30;
            productManager.UpdateProduct(productToUpdate);
        }

        // Delete
        productManager.DeleteProduct(1);

        // Export to Excel
        productManager.ExportToExcel("products.xlsx");  // Save to products.xlsx

        Console.WriteLine("Data exported to products.xlsx");
    }
}