ADO Net C# Tutorial

using System;
using System.Data;
using System.Data.SqlClient;
class ModifyDataTable
{
   static void Main(string[] args)
   {
      string connString = @"server = .\sqlexpress;integrated security = true;database = northwind";
      string sql = @"select * from employee where country = 'UK'";
      SqlConnection conn = new SqlConnection(connString);
      try
      {
         SqlDataAdapter da = new SqlDataAdapter();
         da.SelectCommand = new SqlCommand(sql, conn);
         DataSet ds = new DataSet();
         da.Fill(ds, "employees");
         DataTable dt = ds.Tables["employees"];
         dt.Columns["firstname"].AllowDBNull = true;
         dt.Rows[0]["city"] = "w";
         DataRow newRow = dt.NewRow();
         newRow["firstname"] = "R";
         newRow["lastname"] = "B";
         newRow["titleofcourtesy"] = "Sir";
         newRow["city"] = "B";
         newRow["country"] = "USA";
         dt.Rows.Add(newRow);
         foreach (DataRow row in dt.Rows)
         {
            Console.WriteLine("{0} {1} {2}",
               row["firstname"].ToString().PadRight(15),
               row["lastname"].ToString().PadLeft(25),
               row["city"]);
         }
      }
      catch(Exception e)
      {
         Console.WriteLine("Error: " + e);
      }
      finally
      {
         conn.Close();
      }
   }
}