LINQ到SQL不在

Question

我試圖找到所有的用戶不在朋友用戶朋友列表使用LINQ到SQL。現在我正在將friendslist與系統中的所有用戶進行比較。 Theres得到更好的方式使用linq to sql來做到這一點。感謝您的幫助

// Comparing this to list to see who does not exist. 
// What I would like to do is just use one statement 
// to get the list of non friend users 
var friends = (from x in db.FriendsLists 
       where 
        (x.TheUser == GlobalVariables.User.ID) || 
        (x.TheFriend == GlobalVariables.User.ID) 
       select x).ToList(); 

var allUsersInSystem = (from x in db.Users select x).ToList(); 

Answer 1

var friends = (from x in db.FriendsLists 
            where 
             (x.TheUser == GlobalVariables.User.ID) || 
             (x.TheFriend == GlobalVariables.User.ID) 
            select x.UserID).ToList(); 

    var notInFriendList = from nf in db.Users 
       where !friends.Contains(nf.UserID) 
       select nf; 

的

Answer 2

您可以使用IEnumerable.Except。

實施例：

var notIn = allUsersInSystem.Except(friends);