csharp: datatable get Column datatype or Column Name

/// <summary>        ///列表名        /// </summary>        /// <param name="table"></param>        /// <returns></returns>        public static string GetColumnNames(System.Data.DataTable table)        {            if (table != null)            {                List<string> lstColumn = new List<string>();                foreach (System.Data.DataColumn col in table.Columns)                {                    lstColumn.Add(col.ColumnName);                }                return String.Join(",", lstColumn.ToArray());            }            return string.Empty;            //foreach (DataRow row in table.Rows)            //{            //    foreach (DataColumn column in table.Columns)            //    {            //        ColumnName = column.ColumnName;            //        ColumnData = row[column].ToString();            //    }            //}        }        /// <summary>        /// 数据类型        /// </summary>        /// <param name="table"></param>        /// <returns></returns>        public static string GetColumnNamesType(System.Data.DataTable table)        {            if (table != null)            {                List<string> lstColumn = new List<string>();                foreach (System.Data.DataColumn col in table.Columns)                {                    lstColumn.Add(table.Columns[col.ColumnName].DataType.ToString());                }                return String.Join(",", lstColumn.ToArray());            }            return string.Empty;                    }        /// <summary>        /// 列名和数据类型        /// </summary>        /// <param name="table"></param>        /// <returns></returns>        public static DataTable  GetColumnDataNamesType(System.Data.DataTable table)        {            DataTable dt = new DataTable();            dt.Columns.Add("name", typeof(string));            dt.Columns.Add("datatype", typeof(string));            if (table != null)            {                             foreach (System.Data.DataColumn col in table.Columns)                {                                        dt.Rows.Add(col.ColumnName, table.Columns[col.ColumnName].DataType.ToString());                }                            }            return dt;        }