Modern featured with C#, which is async/await, will be used, and Entity framework with SQLite DB handling user adding, fetching like operation done using simple .Net Core application. Let's create a .NET Core simple application in Visual Studio 2022 and install the SQLite Database package and Entity framework package from Manage NuGet Packages

C#
Microsoft.EntityFrameworkCore
Microsoft.EntityFrameworkCore.Sqlite
Microsoft.EntityFrameworkCore.Tools

Asynchronous methods can help to perform tasks without blocking the running threads. Asynchronous functions generally contain the await expression and Task keyword Task<T> with returns.

Example

C#
static async Task Main(string[] args)
    {
        Console.WriteLine("Fetching data...");
        //    
    }
static async Task<string> FetchDataAsync(string url)
    {
        using (HttpClient client = new HttpClient())
        {
       
            string response = await client.GetStringAsync(url);
            return response;
        }
    }

Create a model Class file for table structure and execute application SQLite DB file will create

Example Model Class

C#
public class ItemContext : DbContext
{
    public ItemContext() { }

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

    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
        optionsBuilder.UseSqlite("Data Source=Item.db");
    }
}

public class Item
  {

      public int Id { get; set; }
      public string Name { get; set; }
      public decimal Price { get; set; }
  }
C#
  public static async Task  ClassDBExample()
  {
      using (var db = new ItemContext())
      {            
          await db.Database.EnsureCreatedAsync();           
          var product = new Item { Name = "PC", Price = 899.99m};
          db.Products.Add(product);
          await db.SaveChangesAsync();         
          var products = await db.Products.ToListAsync();
          foreach (var item in products)
          {
              Console.WriteLine($"ID: {item.Id}, Name: {item.Name}, Price: {item.Price}");
          }
      
          product.Price = 899.99m;
          await db.SaveChangesAsync();

          db.Products.Remove(product);
          await db.SaveChangesAsync();
      }
   }

Output

Output