linq2sql加入不在另一個表中的選擇數據

Question

請不要使用lamba響應。我發現了類似的線程，但仍然需要幫助。

我試圖顯示員工表中不是當前選定經理的僱員的名稱。

我的兩個SQL表的結構是這樣，但是這是假的數據

Employees: 
      pk  name  
      1  bob 
      2  sam 
      3  greg 
      4  kip 
      5  jill 
      6  kelly 
      7  chris 


ExpenseTeamMembers: 

      pk  expMgrPk  empPk  
      1   7   2 
      2   7   5 
      3   7   1 
      4   3   6 
      5   3   4 

因此，如果當前選中（經理變量）爲3我想所有empPks的名字在僱員表中除對於6，4.（凱利，基普）現在unselectedEmps = sam，jill，bob而不是僱員表中所有其他5個名字。

var unselectedEmps = (from u in db.employees 
         join o in db.expenseTeamMembers on u.pk equals o.empPk 
         where o.expMgrPk != mgr 
         select u.name).ToList(); 

       lstAvailable.DataSource = unselectedEmps; 

Answer 1

我們廣泛的討論之後，我想你想要的是這個。

from u in db.Employees 
where !(from e in db.ExpenseTeamMembers 
     where e.expMgrPk == selectedMgr.pk 
     select e.empPk).Contains(u.pk) 
select u.Name 

Answer 2

的問題是，你正在做內部聯接，當你真正需要一個左外連接

見this SO question

Answer 3

我試過以下，它給出了正確的輸出。請您嘗試一下：

List<Employees> emps = new List<Employees>(); 
     emps.Add(new Employees { PK = 1, Name = "bob" }); 
     emps.Add(new Employees { PK = 2, Name = "sam" }); 
     emps.Add(new Employees { PK = 3, Name = "greg" }); 
     emps.Add(new Employees { PK = 4, Name = "kip" }); 
     emps.Add(new Employees { PK = 5, Name = "jill" }); 
     emps.Add(new Employees { PK = 6, Name = "kelly" }); 
     emps.Add(new Employees { PK = 7, Name = "chris" }); 

     List<ExpenseTeamMembers> etm = new List<ExpenseTeamMembers>(); 
     etm.Add(new ExpenseTeamMembers { empPK = 2, ExpMgrPK = 7, PK = 1 }); 
     etm.Add(new ExpenseTeamMembers { empPK = 5, ExpMgrPK = 7, PK = 2 }); 
     etm.Add(new ExpenseTeamMembers { empPK = 1, ExpMgrPK = 7, PK = 3 }); 
     etm.Add(new ExpenseTeamMembers { empPK = 6, ExpMgrPK = 3, PK = 4 }); 
     etm.Add(new ExpenseTeamMembers { empPK = 4, ExpMgrPK = 3, PK = 5 }); 

     var query = from t in 
         (
          from emp in emps 
          join o in etm on emp.PK equals o.empPK into j 
          from k in j.DefaultIfEmpty() 
          select new { Name = k == null ? string.Empty : emp.Name }) 
        where t.Name != string.Empty 
        select t.Name;