For start, there are missing commas

var stories = db.Query("SELECT NewsArticle.NewsId, NewsArticle.NewsDate, NewsArticle.NewsTitle, NewsArticle.NewsText, "
            +   "NewsArticle.NewsPictureUrl, NewsArticle.Newslink, "
            +   "NewsArticle.IsVisible, UserProfile.Membername, UserProfile.Firstname, "
            +   "UserProfile.Lastname, NewsCategory.CategoryName "
            +   "FROM  NewsArticle INNER JOIN "
            +    "ON UserProfile.UserId = Newsarticle.UserId INNER JOIN "
            +     "ON Newscategory.CategoryId - Newsarticle.CategoryId "
            +    "WHERE Newsarticle.Isvisible = 1 "
            +    "ORDER BY Newsarticle.Newsdate DESC");