ADO Net C# Tutorial

using System;
using System.Data;
using System.Data.SqlClient;
    class Program
    {
        static void Main(string[] args)
        {
            string sqlConnectString = "Data Source=(local);Integrated security=SSPI;Initial Catalog=AdventureWorks;";
            string sqlSelect = "SELECT ContactID, FirstName, LastName FROM Person.Contact";
            SqlDataAdapter da = new SqlDataAdapter(sqlSelect, sqlConnectString);
            
            DataTable dt1 = new DataTable();
            da.Fill(dt1);
            DataRow[] dra = new DataRow[dt1.Rows.Count];
            dt1.Rows.CopyTo(dra, 0);
            for (int i = 0; i < dra.Length; i++){
                Console.WriteLine(
                    "ContactID = {0}\tFirstName = {1}\tLastName = {2}",
                    dra[i].Field("ContactID"), dra[i].Field("FirstName"),
                    dra[i].Field("LastName"));
            }
            DataTable dt2 = dra.CopyToDataTable();
            foreach (DataRow row in dt2.Rows)
            {
                Console.WriteLine(
                    "ContactID = {0}\tFirstName = {1}\tLastName = {2}",
                    row["ContactID"], row["FirstName"], row["LastName"]);
            }
            DataTable dt3 = dt1.Clone();
            dra.CopyToDataTable(dt3, LoadOption.Upsert);
            foreach (DataRow row in dt3.Rows)
            {
                Console.WriteLine("ContactID = {0}\tFirstName = {1}\tLastName = {2}",row["ContactID"], row["FirstName"], row["LastName"]);
            }            
        }
    }