組通過與外/左連接在SQL Server 2008

Question

我在1個表的數據作爲

UserID CourseID TestID Result 
1   1  1  P 
1   1  2  P 
2   1  1  F 
2   1  2  F 

這是示出了2名的用戶（用戶ID = 1和2）已採取測試（TestID = 1和2 ）在CourseID = 1

現在，在總的是CourseID有3個試驗（比方說TestID = 1,2,7）作爲

CourseID TestID 
1   1 
1   2 
1   7 

這意味着沒有一個用戶的已測試（TestID = 7）顯示現在我想顯示如下數據

UserID CourseID TestID Result 
1   1  1  P 
1   1  2  P 
1   1  7  null 
2   1  1  F 
2   1  2  F 
2   1  7  null 

我一直在用Group by的左/右外連接嘗試，但無法獲得所需的結果。如何實現？

Answer 1

SQL Fiddle

MS SQL Server 2008的架構設置：

create table Result 
(
    UserID int, 
    CourseID int, 
    TestID int, 
    Result char(1) 
) 
insert into Result values 
(1,   1,  1,  'P'), 
(1,   1,  2,  'P'), 
(2,   1,  1,  'F'), 
(2,   1,  2,  'F') 

create table Course 
(
    CourseID int, 
    TestID int 
) 

insert into Course values 
(1, 1), 
(1, 2), 
(1, 7) 

查詢1：

select U.UserID, 
     C.CourseID, 
     C.TestID, 
     R.Result 
from (
    select distinct UserID 
    from Result 
    ) as U 
    cross apply Course as C 
    left outer join Result as R 
    on R.CourseID = C.CourseID and 
     R.TestID = C.TestID and 
     R.UserID = U.UserID 

Results：

| USERID | COURSEID | TESTID | RESULT | 
--------------------------------------- 
|  1 |  1 |  1 |  P | 
|  1 |  1 |  2 |  P | 
|  1 |  1 |  7 | (null) | 
|  2 |  1 |  1 |  F | 
|  2 |  1 |  2 |  F | 
|  2 |  1 |  7 | (null) | 

注意：如果你有一個表Users你可以用Users as U，而不是取代派生表

(
select distinct UserID 
from Result 
) as U 

。

Answer 2

SELECT uct.UserId, ct.CourseID, ct.TestID, uct.Result 
FROM CourseTest ct 
LEFT JOIN UserCourseTest uct ON uct.CourseID=ct.CourseID AND uct.TestID=ct.TestID