string directory = @"C:\Users\Admin\Documents\visual studio 2010\WebSites\Fotokeramik\App_Data";
SqlConnection conn = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=" + directory + @"\Database.mdf;Integrated Security=True;User Instance=True");

        try
        {
            conn.Open();
            lblConnect.Text = "Databased opened successfully";            
        }
        catch (SqlException ex)
        {
            lblConnect.Text = ex.ToString();
        }
        finally
        {
            conn.Close();
        }

"Server=uXXXXX.mssql.masterhost.ru;Database=uXXXXX;User ID=uXXXXX;Password=PASSWORD" name="SampleString"

[global::System.Data.Linq.Mapping.DatabaseAttribute(Name="Database")]

[global::System.Data.Linq.Mapping.DatabaseAttribute(Name="u123456")]