Question

I’m using Visual Web Developer 2010 Express and SQL Server 2008 R2 Management Studio Express

Hey guys,

Pretty new at C# here. I’m trying to follow this C# ADO.NET tutorial (currently on step 2), and I’m stumped. I’m following all the steps, and everything makes sense to me in it, but whenever I try to debug, it does not show anything (in the sense of the c# methods not printing out a table from Northwind database onto my webpage) in WebApplication1‘s Default.aspx page.

For a while, I thought it was my connection string, conn, and I wasn’t naming the "Data Source" attribute, which from my understanding is the name of the server I’m trying to connect to. It is all on a local machine, and I’m putting the correct server name.. I think. Server name is AZUES-221\JDOESQLSERVER

I’m properly escaping the backward slash, but I still don’t know. Is there something in my coding that’s flawed? Please help!

C# code

using System;
using System.Data;
using System.Data.SqlClient;
using System.Collections.Generic;
using System.Configuration;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.Services;

namespace WebApplication1
{
    public partial class SqlConnectionDemo : System.Web.UI.Page
    {


        protected void Main(object sender, EventArgs e)
        {
            SqlConnection conn = new SqlConnection("Data Source=AZUES-221\\JDOESQLSERVER; Initial Catalog=Northwind; Integrated Security=SSPI");

            SqlDataReader rdr = null;

            try
            {
                conn.Open();
                SqlCommand cmd = new SqlCommand("SELECT * FROM Customers", conn); //passed the connection

                rdr = cmd.ExecuteReader(); // get query results

                while (rdr.Read()) //prints out whatever was
                { Console.WriteLine(rdr[0]); }//selected in the table
            }

            finally
            {
                if (rdr != null)// closes
                { rdr.Close(); }// the reader

                if (conn != null)//closes
                { conn.Close(); }// the connection

            }
        }
    }
}

Thanks in advance

Answer 1

As your example seems to be a WebProject try to put your code within Page_Load eventHandler. Afterwards you should try to print your data to the Debug window or to a control within your webPage.

using System;
using System.Data;
// and all the others ...

namespace WebApplication1
{
  public partial class SqlConnectionDemo : System.Web.UI.Page
  {
    protected void Page_Load(object sender, EventArgs e)
    {
        SqlConnection conn = new SqlConnection("Data Source=AZUES-221\\JDOESQLSERVER; Initial Catalog=Northwind; Integrated Security=SSPI");
        SqlDataReader rdr = null;

        try
        {
            conn.Open();
            SqlCommand cmd = new SqlCommand("SELECT * FROM Customers", conn); 
            rdr = cmd.ExecuteReader(); // get query results

            while (rdr.Read()) //prints out whatever was
            { 
                System.Diagnostics.Debug.WriteLine(rdr[0]); // or on the other hand
                lblOutput.Text += rdr[0];   // as a "quick and dirty" solution!
            }
        }

        finally
        {
            if (rdr != null)// closes
            { rdr.Close(); }// the reader
            if (conn != null)//closes
            { conn.Close(); }// the connection
        }
    }
  }
}

You may it find very useful to have a look at databound controls or just use another type of project (eg winForm, console, …)