what does this mean?

[spars anu]

what does this mean? is it using enums here ? where does it get and set from? please let me know this

namespace FullTilt.Tools.DataAccess.Etc.Entities
{
	public class NoteEntity
	{
		public NoteEntity()
			: this(0, 0, 0, 0, 0, String.Empty, String.Empty, DateTime.Now)
		{
		}

		public NoteEntity(Int32 ix, Int32 playerIx, Int32 adminIx, int actionKey, 
				NoteType noteType, String text, String actionDescription, DateTime createdDate)
		{
			Ix = ix;
			PlayerIx = playerIx;
			AdminIx = adminIx;
			ActionKey = actionKey;
			ActionDescription = actionDescription;
			NoteType = noteType;
			Text = text;
			CreatedDate = createdDate;
		}

		public virtual Int32 Ix { get; set; }

		public virtual Int32 AdminIx { get; set; }

		public virtual Int32 PlayerIx { get; set; }

		public virtual int ActionKey { get; set; }

		public virtual NoteType NoteType { get; set; }

		public virtual String Text { get; set; }

        public virtual String ActionDescription { get; set; }

		public virtual DateTime CreatedDate { get; set; }
	}
}

[Matthew Brown]

That's using a C# mechanism called "anonymous properties". What it does is create a private member variable behing the scenes, and generate corresponding getters/setters for the properties. It's a nice shorthand - I was never particularly sold on the idea of properties as an improvement on get/set methods until this was introduced.

For example, this:

public virtual int ActionKey { get; set; }

Is roughly equivalent to this:

private int _actionKey;
public virtual int ActionKey { 
    get {
        return _actionKey; 
    }
    set {
        _actionKey = value;
    }
}

There are no Enums unless one of the types you're referring to (e.g. NoteType) is an enum.

(I've formatted your code to make it easier to follow - you can do that yourself: see UseCodeTags).

[spars anu]

Can you also explain me what does ?? mean in the following code:

public virtual void AddPlayerNote(int playerIdentifier, String note, int impersonationIdentifier)
{
	var playerNote = new NoteEntity
		{
			PlayerIx = playerIdentifier,
			Text = (note ?? string.Empty),
			AdminIx = impersonationIdentifier,
			NoteType = NoteType.PLAYER_NOTE,
			ActionKey = (int)ActionKey.FraudBatch,
		};
	etcDataStore.CreatePlayerNote(playerNote);
}

[Matthew Brown]

That's just C# property initializer syntax. These are standard features of the language (as of C#3.0, I think) - they'll be included in any introductory book on the language. Have a guess - what does it look like it does?

[spars anu]

public enum ActionKey
{
[EnumMember]
FraudBatch = 139,
}
I defined enum in this way.Can i implement in the above way

[Matthew Brown]

I'm not sure what you mean. Have you tried it? That's usually the best and most reliable way of finding out if you can do something.