DataReader、DataSet、DataView循环读取整表或单列

string sql = "delete from Users where ID=3";
        SqlConnection conn = new SqlConnection(sqlConnString);
        SqlCommand cmd = new SqlCommand(sql, conn);
        try
        {
            conn.Open();
            sqldataReader dr=cmd.ExecutReader();

            while(dr.Reader())

            {

               responser.write(dr["Name"]);

            }

        }
        catch (SqlException sqlex)
        {
            Response.Write(sqlex.Message + "<br>");
        }
        finally
        {
            conn.Close();
        }

2、DataAdapter和DataSet、DataView读取单列数据

string sql = "select * from Users";
        SqlConnection conn = new SqlConnection(sqlConnString);
        SqlDataAdapter da = new SqlDataAdapter(sql, conn);
        try
        {
            conn.Open();
            DataSet ds = new DataSet("Users");
            da.Fill(ds, "Users");
            DataView dv = ds.Tables[0].DefaultView;

            //DataView读取单列
            for (int i = 0; i < dv.Table.Rows.Count; i++)
            {
                Response.Write(dv.Table.Rows[i]["ID"].ToString()+" "+"<br>");
            }

            //DataSet读取单列
            foreach (DataRow row in ds.Tables[0].Rows)
                Response.Write(row["Name"].ToString()+" "+row[0].ToString()+"<br>");
            DataList1.DataSource = dv;
            DataList1.DataBind();
            GridView1.DataSource = ds;
            GridView1.DataBind();
        }
        catch (SqlException exception)
        {
            Response.Write(exception.Message + "<br>");
        }
        finally
        {
            conn.Close();
        }

循环读取dataset

DataSet ds = new DataSet();

  foreach (DataTable dt in ds.Tables)
  {
  foreach (DataRow dr in dt.Rows)
  {
  foreach (DataColumn dc in dt.Columns)
  {
  System.Console.Write(dr[dc]);
  }
  }
  }