Member Avatar for zack_falcon

I've written a sales and inventory program in C# that makes use of SQL Server, because I've heard it functions well over LAN connections (haven't tried it yet).

I've... let's say... hardwired the my connection string into the program. I have a notepad connection.ini file that has the connection string, which goes something like this:

Server=MY-PC\SQLEXPRESS;Database=dBaseAIS;Trusted_Connection=True;

So, everytime I have to connect to the SQL server, I use this:

string pathCheck = Directory.GetCurrentDirectory();
                    pathCheck = pathCheck.Replace(@"\", "/");
                    pathCheck = pathCheck.Replace(@"/bin/Debug", "/App_Data/connection.ini");
                    StreamReader sr = File.OpenText(pathCheck);

                    try
                    {
                        string sql = "DELETE FROM takeoffList;";
                        SqlConnection myConn = new SqlConnection(sr.ReadLine().ToString());
                        myConn.Open();
                        SqlCommand myComm = new SqlCommand(sql, myConn);
                        myComm.ExecuteNonQuery();
                        MessageBox.Show("Item has been deleted from database.", "AIS");
                    }
                    catch (Exception ex)
                    {
                        MessageBox.Show(ex.ToString());
                    }

The above code has no problems, whatsoever. The program works fine, but I needed Crystal Reports to finish it. So I tried to follow this page:

http://infynet.wordpress.com/2010/10/06/crystal-report-in-c/

Now, for some reason, that method requires a Data Connection (which up to this point, I assumed I had). When opening up Server Explorer in C#, the database is not there.

So I tried to create a new database via C# (Server Explorer), if only so I can see something in my Data Connections. Then it tells me "Name Pipes Provider, error 40 - Could not open a connection to SQL Server."

At this point, I have no idea what to do, or what happened (my program still runs fine).

I have Visual Studio 2005, Sql Management Studio Express (with TCP / IP and Name Pipes set to Enabled) and I'm running on Windows 7 32-bit (with sqlservr.exe and sqlbrowser.exe exceptions in the firewall).

Could anyone please tell me what I'm doing wrong? Thanks.

Edited by zack_falcon because: n/a
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  • Latest Post Latest Post by Mitja Bonca

Dani AI

Generated

Good catch, — the symptom you saw is exactly the common named‑instance problem: SQL Server Express installs as a named instance (usually SQLEXPRESS), so using only the machine name points at the default instance (which isn’t there). Your program worked because its connection string specified the instance; Server Explorer failed until you typed the full server name (MY‑PC\SQLEXPRESS). The “Named Pipes Provider, error 40” typically means the client could not locate or reach the specified instance (wrong name, instance not running, protocol or firewall blocking, or SQL Browser not available).

Practical checklist to avoid this in future:

  • Verify the service exists and is running (look for "SQL Server (SQLEXPRESS)" in Services or SQL Server Configuration Manager).
  • Ensure SQL Server Browser is started if you rely on instance discovery or dynamic ports.
  • In SQL Server Configuration Manager enable the network protocols you need (Shared Memory for local, TCP/IP for LAN, Named Pipes if you use it) and restart the SQL Server service after changes.
  • Open the right firewall ports: either the instance TCP port or UDP 1434 for SQL Browser (named instances often use dynamic ports).
  • When connecting from Visual Studio’s Server Explorer, type the server as MachineName\InstanceName (or .\SQLEXPRESS or (local)\SQLEXPRESS when local).

A couple of extra notes: if you distribute the app on a LAN prefer a proper central DB server (or a static port) and consider SQL authentication for cross‑machine scenarios. Also watch out for using AttachDbFilename in desktop apps — Visual Studio can copy an .mdf into the bin folder so you end up editing a copy.

Storing the connection string in app.config makes switching targets easier. Example:

<configuration>
  <connectionStrings>
    <add name="MyConn" connectionString="Data Source=.\SQLEXPRESS;Initial Catalog=YourDb;Integrated Security=True;" providerName="System.Data.SqlClient" />
  </connectionStrings>
</configuration>

And read it in C# (add reference to System.Configuration in VS2005):

string conn = ConfigurationManager.ConnectionStrings["MyConn"].ConnectionString;
using(var cn = new SqlConnection(conn)) { cn.Open(); /* ... */ }

This explains why the manual instance name fixed the issue and gives a few extra hardening/troubleshooting steps. Thanks to for prompting closure — the thread is resolved by specifying the instance.

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Member Avatar for zack_falcon

Nevermind. I got it myself. :)

Now, here's what I *think* I did wrong.

When the Data Connection is asking for a Server, I clicked the dropdown list of available servers in my PC, which is, quite unimaginatively, named MY-PC.

After looking at my notepad connection string and the error regarding the instance, I simply added a "\SQLEXPRESS" to the end of the server name, so the full server name is now:

MY-PC\SQLEXPRESS

And now my database appears in the Data Connections. Yey!

If any other trouble pops up, I'll see if I can keep this thread open to post it in. I might be asked to mark this as solved.

Member Avatar for Mitja Bonca

If you got it, just mark this thread as answered. Thx in advance.

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