从已获取数据的DataTable中提取固定列

DataTable dt = new DataTable();            dt.Columns.Add("id",typeof(Int32));            dt.Columns.Add("UserName", typeof(string));            dt.Columns.Add("UserPwd",typeof(string));            dt.Columns.Add("UserSex", typeof(string));            DataRow dr = dt.NewRow();            dr[0] = "1";            dr[1] = "admin";            dr[2] = "123";            dr[3] = "男";            dt.Rows.Add(dr);            DataTable newTable = dt.DefaultView.ToTable(false, new string[] { "id", "UserName"});

参考：http://tech.it168.com/KnowledgeBase/Articles/9/0/1/901f89bcfff296a73c7c4f91117cc177.htm

select 方法能根据条件获取行 无法获取列