//string sql1 = "SELECT dcId,dcName,dcType,dcLength,CASE WHEN dcIsNull=1 THEN '√' ELSE '×'END AS dcIsNull,CASE WHEN dcDefault=0 THEN NULL ELSE dcDefault END AS dcDefault,dcRemark,ddcId FROM DocumentChilds WHERE ddcId='" + e.Node.Tag + "' ORDER BY dcName";
                //dts = DBHelper.getDatatable(sql1);
             
                
                var v4 = from dc in cx.DocumentChilds where dc.ddcId == Convert.ToInt32(e.Node.Tag) select new 
                {   
                    dc.dcId,
                    dc.dcName,
                    dc.dcType,
                    dc.dcLength,
                    dc.dcIsNull,
                    dc.dcDefault,
                    dc.dcRemark,
                    dc.ddcId
                };
                dts = v4.ToDataTable(cx);

 /// <summary>
        /// 对 System.Data.Linq 的扩展
        /// 从给定的Linq To SQL 查询获取 DataTable 对象 
        /// </summary>
        /// <param name="source"></param>
        /// <param name="db"></param>
        /// <returns></returns>
        public static DataTable ToDataTable(this IQueryable source, DataClasses1DataContext db)
        {
            //将 LinqToSQL查询传递给 GetCommand（）以获取DbCommand对象
            DbCommand cmd = db.GetCommand(source);
            //打开数据库链接，这里可以进一步扩展，比如传递进来自己定义的继承自 DbConnection 的对象
            if (db.Connection.State == ConnectionState.Closed)
                db.Connection.Open();
            //声明 DataTable 对象
            DataTable dt = new DataTable();
            //调用DataTable 对象的 Load方法 ，从 DbDataReader 对象加载数据。
            dt.Load(cmd.ExecuteReader());
            //关闭DbConnection 链接 
            db.Connection.Close();

            return dt;
        }