提问：错误提示--命名空间“System.Web”中不存在类型或命名空间名称“UI”(是缺少程序集引用吗?)　如何解决？？

using System;

using System.Collections;

using System.Web.UI.WebControls;

namespace org.ct.gt.bd.Data

{

	#region BQSJY



	/// <summary>

	/// BQSJY object for NHibernate mapped table 'BQSJY'.

	/// </summary>

	public class BQSJY : System.IComparable

		{

		#region Member Variables

		

		protected int _id;

		protected string _sJYBSM;

		protected string _sJYMC;

		protected int _lX;

		protected string _mS;

		protected static String _sortExpression = "Id";

		protected static SortDirection _sortDirection = SortDirection.Ascending;



		#endregion



		#region Constructors



		public BQSJY() { }



		public BQSJY( string sJYBSM, string sJYMC, int lX, string mS )

		{

			this._sJYBSM = sJYBSM;

			this._sJYMC = sJYMC;

			this._lX = lX;

			this._mS = mS;

		}



		#endregion



		#region Public Properties



		public int Id

		{

			get {return _id;}

			set {_id = value;}

		}



		public string SJYBSM

		{

			get { return _sJYBSM; }

			set

			{

				if ( value != null && value.Length > 50)

					throw new ArgumentOutOfRangeException("Invalid value for SJYBSM", value, value.ToString());

				_sJYBSM = value;

			}

		}



		public string SJYMC

		{

			get { return _sJYMC; }

			set

			{

				if ( value != null && value.Length > 100)

					throw new ArgumentOutOfRangeException("Invalid value for SJYMC", value, value.ToString());

				_sJYMC = value;

			}

		}



		public int LX

		{

			get { return _lX; }

			set { _lX = value; }

		}



		public string MS

		{

			get { return _mS; }

			set

			{

				if ( value != null && value.Length > 200)

					throw new ArgumentOutOfRangeException("Invalid value for MS", value, value.ToString());

				_mS = value;

			}

		}



        public static String SortExpression

        {

            get { return _sortExpression; }

            set { _sortExpression = value; }

        }



        public static SortDirection SortDirection

        {

            get { return _sortDirection; }

            set { _sortDirection = value; }

        }

		#endregion

		

        #region IComparable Methods

        public int CompareTo(object obj)

        {

			if (!(obj is BQSJY))

				throw new InvalidCastException("This object is not of type BQSJY");

			

			int relativeValue;

			switch (SortExpression)

			{

				case "Id":

					relativeValue = this.Id.CompareTo(((BQSJY)obj).Id);

					break;

				case "SJYBSM":

					relativeValue = (this.SJYBSM != null) ? this.SJYBSM.CompareTo(((BQSJY)obj).SJYBSM) : -1;

					break;

				case "SJYMC":

					relativeValue = (this.SJYMC != null) ? this.SJYMC.CompareTo(((BQSJY)obj).SJYMC) : -1;

					break;

				case "LX":

					relativeValue = (this.LX != null) ? this.LX.CompareTo(((BQSJY)obj).LX) : -1;

					break;

				case "MS":

					relativeValue = (this.MS != null) ? this.MS.CompareTo(((BQSJY)obj).MS) : -1;

					break;

                default:

                    goto case "Id";

			}

            if (BQSJY.SortDirection == SortDirection.Ascending)

				relativeValue *= -1;

			return relativeValue;

		}

		#endregion

	}



	#endregion

}