ok so this is my code:
private void iDListBox_SelectedIndexChanged(object sender, EventArgs e)
{
string connectionString = GetConnectionString();
using (SqlConnection connection = new SqlConnection(connectionString))
{
SqlCommand cmd = new SqlCommand("SELECT * FROM Table1 WHERE Naam=@.Naam", connection);
cmd.Parameters.AddWithValue("@.Naam", iDListBox.SelectedValue);
connection.Open();
SqlDataReader reader = cmd.ExecuteReader();
if (reader.Read())
{
naamTextBox.Text = reader.GetString(1);
}
reader.Dispose();
connection.Dispose();
}
}
static private string GetConnectionString()
{
return "Data Source=(local);Initial Catalog=AdventureWorks;"
+ "Integrated Security=SSPI;";
}
but when I change the selected index of the listbox, then this error comes up:
System.Data.SqlClient.SqlException was unhandled
Message="An error occured while setting up a connection with the server. At making a connection with SQL server 2005, this jamming is possibly caused by the fact that at the standardinstitutions of SQL server no external connections have been permitted (provider: Provider of named pipes, error: 40 - no connection with SQL could open server)"
If the error sounds a bit weird, sry I tried to translate as most of my errors come in my language
someone knows what the problem is and a solution to it?
(btw sry if this is in the wrong part of the sql forum, but there are so much parts, I didn't know which to choose lol 
thx in advance
Please see http://blogs.msdn.com/sql_protocols/archive/2007/03/31/named-pipes-provider-error-40-could-not-open-a-connection-to-sql-server.aspx to see if any of the suggestions solves your case.
Jimmy
