Question

Im trying to create a field called Owner in my table where You select the AddedBy field where parentID is equal to the PostID so far it only prints out the first field and the second is always null. Im doing a subquery on a query. Im trying to get the parent AddedBy field

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

Im trying to get a count of all posts that related to the PostID joinded by ParentID in a join but im getting an error so when i do a group by of all the Fields i still get the error:- error is below

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; 

i get the following error:

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.

PostID, ParentID, AddedBy, Title, Path_String:- PostID is IdentityColumn Path_String is in this format 1/, 1/1/, 1/1/2 and ParentID is an integer

    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

Should be this

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;