ADO Net C# Tutorial

using System;
using System.Data;
using System.Data.SqlClient;
class MainClass
{
   static void Main(string[] args)
   {
      string connString = @"server = .\sqlexpress;integrated security = true;database = northwind";
      string qry = @"select * from employees where country = 'UK'";
      string del = @"delete from employees where employeeid = @employeeid";
      SqlConnection conn = new SqlConnection(connString);
      try
      {
         SqlDataAdapter da = new SqlDataAdapter();
         da.SelectCommand = new SqlCommand(qry, conn);
         DataSet ds = new DataSet();
         da.Fill(ds, "employees");
         DataTable dt = ds.Tables["employees"];
         SqlCommand cmd = new SqlCommand(del, conn);
         cmd.Parameters.Add("@employeeid",SqlDbType.Int,4,"employeeid");
         string filt = @"firstname = 'R' and lastname = 'B'";
         foreach (DataRow row in dt.Select(filt))
         {
            row.Delete();
         }
         da.DeleteCommand = cmd;
         da.Update(ds, "employees");
         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();
      }
   }
}