.net 手动建DataTable 获取DataTable列名 修改DataTable 列的顺序

//创建 表
DataTable tables = new DataTable();
//添加 创建 列
//第一列
DataColumn cums = new DataColumn();
cums.ColumnName = "UserName";
cums.DataType = typeof(string);
tables.Columns.Add(cums);
cums = new DataColumn();
cums.ColumnName = "Age";
cums.DataType = typeof(string);
tables.Columns.Add(cums);
tables.Columns.Add("Address", typeof(string));  这种用的较多
tables.Columns["Address"].SetOrdinal(0);  //修改DataTable 列的顺序
string[] columnNames = GetColumnsByDataTable(tables);
string ss = columnNames[0];   

        /// <summary>
        /// 根据datatable获得列名
        /// </summary>
        /// <param name="dt">表对象</param>
        /// <returns>返回结果的数据列数组</returns>   
       public  string[] GetColumnsByDataTable(DataTable dt)
        {
            string[] strColumns = null;
            if (dt.Columns.Count > 0)
            {
                int columnNum = 0;
                columnNum = dt.Columns.Count;
                strColumns = new string[columnNum];
                for (int i = 0; i < dt.Columns.Count; i++)
                {
                    strColumns[i] = dt.Columns[i].ColumnName;
                }
            }
            return strColumns;
        }