如何一次使用LINQ to SQL連接多個表？

Question

Users: 
    userid name email 
    1   venkat v@g.com 
    2   venu  ve@g.com 
    3   raghu r@g.com 

patners: 
id userid patnerid status 
1  1  2   1 
2  1  3   1 

location: 
id userid lat lon 
1  1  12.00 13.00 
2  2  14.00 12.00 
3  3  14.00 14.23 

如果用戶發送請求爲userid = 1，那麼我需要拉他的patters [2,3] lat，lon值和他們的名字... 如何實現這一目標？ 謝謝，

Answer 1

您需要使用LINQ Join構造。即使在這個網站上也有plenty of examples。

Answer 2

 

var locations = from u in Context.users 
       join p in u.partners 
       join l in p.locations 
       where u.userid = 1 
       select l; 

Answer 3

var query = from p in parters 
      join u in users on p.userid equals u.userid 
      where u.userid == 1 
      select new 
      { 
       //properties of p & u 
      } 

Answer 4

東西在下一行應該這樣做。還請查看LINQ 101 samples

var result = from u in db.Users 
      join p in db.Partners on u.userid equals p.userid 
      join l in db.locations on l.userid equals u.userid 
      where u.userid == 1 
      select new 
        { 
         UserId= u.userID, 
         PatnerID = p.patnerid 
        };