Simple Connected DB Example

The following code can be copied and compiled in a C# commandline project:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data.SqlClient;

namespace SimpleConnected
{
    /// <summary>
    /// This simple program demonstrates how to access rows of data from a 
    /// database using SQL commands in a connected scenario.
    /// </summary>
    class Program
    {
        static void Main(string[] args)
        {
            /*
             * First we have to identify the server and how we will connect to 
             * it. The "Data Source" gives the name and instance of the server
             * which in this case is the SQLExpress instance on the localhost.
             * The "Initial Catalog" identifies the Database. We could use a
             * username and password if we had used database security. But in 
             * this case we used "Security Support Provider Interface" (SSPI)
             * to authenticate the currently logged in user.
             */
            string constr = @"Data Source=localhost\SQLExpress; Initial Catalog=VRG; Integrated Security=SSPI;";

            /*
             * The above is just a string, we still need a connection to the 
             * database. We do this using the SqlConnection object from
             *      System.Data.SqlClient (see the using statement)
             * We feed the SqlConnection object the connection string so that 
             * it knows what to connect to and how.
             */ 
            SqlConnection con = new SqlConnection(constr);
            /*
             * The connection isn't much good unless you open it. This opens
             * the connection so that we can execute commands against it.
             */ 
            con.Open();
            /*
             * Now that we have an open connection, lets look at how we can use
             * it. TO do this we create a SqlCommand object, again from
             *      System.Data.SqlClient
             * In order for the Command object to do much it has to have access
             * to the connection object so we define the command using SQL and 
             * give it the connection.
             */ 
            SqlCommand com = new SqlCommand("SELECT * FROM Customer",con);
            /*
             * There are other options that we could give command, but this is 
             * enough to start. The command doesn't execute until you actually
             * tell it to, which we do next. We can execute it in several 
             * different ways. Lets use the command completion to look at some
             * of them...
             */ 
            SqlDataReader sdr = com.ExecuteReader();
            /*
             * Since we chose to get a DataReader we can now loop through the 
             * rows in the database 
             */ 
            while (sdr.Read())
            {
                /*
                 * The rows are accessed directly from the DataReader using 
                 * either an integer or string index. Here I've actually 
                 * trimmed the results so that I don't get fixed length strings
                 */ 
                Console.WriteLine("Name: {0}, Email: {1}", sdr["Name"].ToString().Trim(), sdr["Email"].ToString().Trim());
            }
            /*
             * Don't forget to clean up after yourself!
             */ 
            sdr.Close();
            con.Close();
        }
    }
}