Dear all,

I am really new to C# .NET and SQL Server, I usually manage to find all my informations thanks to existing posts, but I have to admit I'm actually stuck and a bit lost with all the resources available.

I am actually developing a Windows Forms Application with Visual C# Express 2010 which would use (read/write) data from a SQL Server 2008 Express DB

I have created my DB with SQL Server Management Studio (2008 Express), I understand the instance is named ATLELAG786576\SQLEXPRESS My DB is called 'TEST'

Looking at my DB 'TEST' Properties in SQL Server Management Studio (2008 Express): Under Files, I am (ATLE\bneveux) the owner of the DB

Looking under Security, Logins, Mylogin (ATLE\bneveux) My default DB is 'TEST' Server roles are 'public' + 'sysadmin' User Mapping DB 'TEST' User 'dbo' Default Schema 'dbo'

In my C# application

app.config:
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<?xml version="1.0" encoding="utf-8" ?> <configuration>
    <configSections>
    </configSections>
    <connectionStrings>
        <add name="connectionStringTestDb"
            connectionString="Data Source=ATLELAG786576\SQLEXPRESS;Initial Catalog=D:\Microsoft SQL Server\MSSQL10.SQLEXPRESS\MSSQL\DATA\TEST.mdf;Integrated Security=True;Connect Timeout=30;User Instance=False"
            providerName="System.Data.SqlClient" />
    </connectionStrings> </configuration>
dbConnection.cs:
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using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;
using System.Data.SqlClient;
using System.Configuration;
namespace SQLServerConnectionDemo
{
    class dbConnection
    {
        public static SqlConnection newCon;
        public static string connectionStringTestDb = ConfigurationManager.ConnectionStrings["connectionStringTestDb"].ConnectionString;
        public static SqlConnection GetConnection()
        {
            newCon = new SqlConnection(connectionStringTestDb);
            return newCon;
        }
    }
}
dbAccess.cs:
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using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;
using System.Data.SqlClient;
namespace SQLServerConnectionDemo
{
    class dbAccess
    {
        SqlConnection conn;
        public dbAccess()
        {
            conn = dbConnection.GetConnection();
        }
        //Method insert new in tblEmployees
        public void addEmployee(string Id, string Name, string Email)
        {
            if (conn.State.ToString() == "Closed")
            {
                conn.Open();
            }
            SqlCommand newCmd = conn.CreateCommand();
            newCmd.Connection = conn;
            newCmd.CommandType = CommandType.Text;
            newCmd.CommandText = "INSERT INTO tblEmployees VALUES ('"+ Id +"','"+ Name +"','"+ Email +"')";
            newCmd.ExecuteNonQuery();
        }
    }
}
in a form formEmployeeAdd.cs:
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using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace SQLServerConnectionDemo
{
    public partial class formEmployeeAdd : Form
    {
        dbAccess access = new dbAccess();
        public formEmployeeAdd()
        {
            InitializeComponent();
        }
        private void btnInsert_Click(object sender, EventArgs e)
        {
            access.addEmployee(txtId.Text, txtName.Text, txtEmail.Text);
            MessageBox.Show("Data successfully added");
        }
    }
}
And here the error message i always get when trying to run this process:
System.Data.SqlClient.SqlException (0x80131904): Cannot open database "D:\Microsoft SQL Server\MSSQL10.SQLEXPRESS\MSSQL\DATA\TEST.mdf" requested by the login. The login failed. Login failed for user 'ATLE\bneveux'.

Note that I have never really been able to add my Data Source in Visual C# 2010 Express so I could manage the DB from VS, I always get the following error message:
Unable to open the physical file "D:\Microsoft SQL Server\MSSQL10.SQLEXPRESS\MSSQL\DATA\TEST.mdf". Operating system error 32: "32(Le processus ne peut pas accéder au fichier car ce fichier est utilisé par un autre processus.)". An attempt to attach an auto-named database for file D:\Microsoft SQL Server\MSSQL10.SQLEXPRESS\MSSQL\DATA\TEST.mdf failed. A database with the same name exists, or specified file cannot be opened, or it is located on UNC share.

Thank you for your expertise

Brice