C#

IFormatProvider formatter = CultureInfo.InvariantCulture.NumberFormatInfo;
decimal d = ((IConvertable)DBNull.Value).ToDecimal(null);

using System;

SqlCommand cmd = sqlConnection1.CreateCommand();
cmd.CommandText = "UPDATE MyTable SET DecimalField = @DecimalField WHERE ID = 1";
SqlParameter decimalField = cmd.Parameters.Add("@DecimalField", SqlDbType.Decimal);
decimalField.Value = myDecimal == 0m ? DBNull.Value : myDecimal;

"You can have everything in life you want if you will just help enough other people get what they want." --Zig Ziglar

The Second EuroCPian Event will be in Brussels on the 4th of September

Can't manage to P/Invoke that Win32 API in .NET? Why not do interop the wiki way!

using System;
using Interop.Scripting;

public class Test
{
  static void Main()
  {
    IDictionary dict = new DictionaryClass();
    Add(dict, "a", 1);
    Add(dict, "b", 2);
    Add(dict, "c", 3);

    object[] keys = (object[])dict.Keys();
    for (int i=0; i<keys.Length; i++)
    {
      object key = keys[i];
      object value = dict.get_Item(ref key);
      Console.WriteLine("{0}: {1}", key, value);
    }

    object a = "a";
    Console.WriteLine("\na={0}", dict.get_Item(ref a));
  }

  static void Add(IDictionary dict, object key, object value)
  {
    dict.Add(ref key, ref value);
  }
}

tlbimp.exe /out:Interop.Scripting.dll scrrun.dll

using IDict = Interop.Scripting.IDictionary;