General trees persisted in relational databases

using System;
using System.Collections;

public class TreeNode {
	TreeNode parent;
	object userObject;
	IList children = new ArrayList();
	
    public TreeNode(object userObject) {
		this.userObject = userObject;
    	parent = null;
    }
    
    public void Add(TreeNode child) {
    	children.Add(child);
    	child.Parent = this;
    }
    
    public TreeNode Parent {
    	get {
    		return parent;
    	} set {
    		this.parent = value;
    	}
    }
    
    public int ChildCount {
    	get {
    		return children.Count;
    	}
    }
    
    public IList Children {
    	get {
    		return children;
    	}
    }
}