通過字段獲得父項的子查詢

Question

我試圖在我的表中創建一個名爲Owner的字段，其中您選擇了AddedBy字段，其中parentID等於PostID到目前爲止它只打印出第一個字段，第二個始終爲空。我在查詢中做一個子查詢。我試着去獲取父AddedBy場

SELECT Level, Sequence, PostID, AddedBy, Title, ParentID, Path_String, 
    CASE WHEN ParentID IS NULL THEN 
     AddedBy 
    ELSE 
     (SELECT AddedBy FROM cte o WHERE o.PostID = ParentID) 
    END AS Owner 
FROM cte order by Sequence 

我試着去獲取有關通過PARENTID在joinded的帖子ID的所有帖子的計數的加入，但IM得到一個錯誤，所以，當我通過做一組中的所有場我仍然得到錯誤： - 錯誤下面是

SELECT s.Level, s.Sequence, s.PostID, s.AddedBy, 
s.Title, s.ParentID, s.Path_String, 
Owner = COALESCE(o.AddedBy, s.AddedBy), COUNT(r.ParentID) 
FROM cte AS s 
LEFT OUTER JOIN cte AS o 
ON s.ParentID = o.PostID 
RIGHT join cte AS r 
on s.PostID = r.ParentID 
ORDER BY s.Sequence; 

我得到以下錯誤：

Msg 8120, Level 16, State 1, Procedure sproc_GetPostsByThread, Line 34 
Column 'cte.Level' is invalid in the select list because it is not 
contained in either an aggregate function or the GROUP BY clause. 

帖子ID，PARENTID，AddedBy，標題，Path_String： - 是帖子ID IdentityColumn Path_String我S IN此格式1/1/1 /，1/1/2和PARENTID是整數

Level  Sequence     PostID  AddedBy Title  ParentID Path_String Owner Count           

---

1  00000003       3   kirkdm  test  NULL  3/   kirkdm 1 
2  0000000300000005     5   MikeDM  re: test 3   3/5/   kirkdm 2 
3  000000030000000500000008   8   Joelene re: test 5   3/5/8/  MikeDM 2 
3  000000030000000500000009   9   kirkdm  re: test 5   3/5/9/  MikeDM 1 
4  00000003000000050000000900000010 10   Crushanin re: test 9   3/5/9/10/ kirkdm 1 

應該是這

Level  Sequence          PostID  AddedBy  Title  ParentID Path_String  Owner  Count column here 

---

1   00000003          3   kirkdm  test  NULL  3/    kirkdm 
2   0000000300000005        5   MikeDM  re: test 3   3/5/   kirkdm 
3   000000030000000500000008      8   Joelene  re: test 5   3/5/8/   MikeDM 
4   00000003000000050000000800000014    14   Christian re: test 8   3/5/8/14/  Joelene 
4   00000003000000050000000800000015    15   Zeke   re: test 8   3/5/8/15/  Joelene 
3   000000030000000500000009      9   kirkdm  re: test 5   3/5/9/   MikeDM 
4   00000003000000050000000900000010    10   Crushanin re: test 9   3/5/9/10/  kirkdm 
5   0000000300000005000000090000001000000011  11   Tim   re: test 10   3/5/9/10/11/ Crushanin 

Answer 1

SELECT s.Level, s.Sequence, s.PostID, s.AddedBy, 
    s.Title, s.ParentID, s.Path_String, 
    Owner = COALESCE(o.AddedBy, s.AddedBy) 
FROM cte AS s 
LEFT OUTER JOIN cte AS o 
ON s.ParentID = o.PostID 
ORDER BY s.Sequence;