public string connectionString = @"Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\namedatabase.mdf;Integrated Security=True;Connect Timeout=30;User Instance=True";
        public SqlConnection connection = new SqlConnection();     
        public BackUp()
        {
            InitializeComponent();

کد زیر را برای اتصال به دیتابیس باید بنویسید.
            connection.ConnectionString = connectionString;
        }
                               
      
        public void backup(string filename)
        {
            string query = "Backup database [" + System.Windows.Forms.Application.StartupPath + "\\AmlakT.mdf] TO DISK='" + filename + "'";
            SqlCommand command = new SqlCommand(query, connection);
            command.Connection.Open();
            command.ExecuteNonQuery();
            command.Connection.Close();
        }