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Editorial Team
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Asked: 2026-06-14T10:52:20+00:00

Here is my table +————+———–+—————+————–+ | CommentId | ParentId | Timestamp | CommentText |

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Here is my table

+------------+-----------+---------------+--------------+
| CommentId  | ParentId  |  Timestamp    | CommentText  |
+------------+---------+-----------+--------------------+
|          1 |      NULL |  Jan 1 2:00pm |          a   |
|          2 |      NULL |  Jan 1 2:01pm |          b   |
|          3 |         1 |  Jan 1 3:03pm |          c   |
|          4 |         2 |  Jan 1 5:00pm |          d   |
|          5 |         2 |  Jan 1 5:01pm |          e   |
|          6 |      NULL |  Jan 1 8:00pm |          f   |
|          7 |         1 |  Jan 1 7:00pm |          g   |
|          8 |         6 |  Jan 1 9:04pm |          h   |
|          9 |         1 |  Jan 1 8:05pm |          i   |
|         10 |      NULL |  Jan 1 9:04pm |          k   |
+------------+-----------+---------------+--------------+

Currently I am using the following SQL to return the comments ordered by parent

SELECT c.*
FROM Comments c
ORDER BY COALESCE(c.ParentId, c.Id)

The result is this:

+------------+-----------+---------------+--------------+
| CommentId  | ParentId  |  Timestamp    | CommentText  |
+------------+---------+-----------+--------------------+
|          1 |      NULL |  Jan 1 2:00pm |          a   |
|          3 |         1 |  Jan 1 3:03pm |          c   |
|          7 |         1 |  Jan 1 7:00pm |          g   |
|          9 |         1 |  Jan 1 8:05pm |          i   |    
|          2 |      NULL |  Jan 1 2:01pm |          b   |    
|          4 |         2 |  Jan 1 5:00pm |          d   |
|          5 |         2 |  Jan 1 5:01pm |          e   |
|          6 |      NULL |  Jan 1 8:00pm |          f   |    
|          8 |         6 |  Jan 1 9:04pm |          h   |    
|         10 |      NULL |  Jan 1 9:04pm |          k   |
+------------+-----------+---------------+--------------+

I need to get the results in a Descending timestamp order. The result set should look like:

 +------------+-----------+---------------+--------------+
| CommentId  | ParentId  |  Timestamp    | CommentText  |
+------------+---------+-----------+--------------------+         
|         10 |      NULL |  Jan 1 9:04pm |          k   |
|          6 |      NULL |  Jan 1 8:00pm |          f   |    
|          8 |         6 |  Jan 1 9:04pm |          h   |    
|          2 |      NULL |  Jan 1 2:01pm |          b   |    
|          5 |         2 |  Jan 1 5:01pm |          e   |
|          4 |         2 |  Jan 1 5:00pm |          d   |
|          1 |      NULL |  Jan 1 2:00pm |          a   |
|          9 |         1 |  Jan 1 8:05pm |          i   |
|          7 |         1 |  Jan 1 7:00pm |          g   |
|          3 |         1 |  Jan 1 3:03pm |          c   |    
+------------+-----------+---------------+--------------+

The following does not work:

SELECT c.*
FROM Comments c
ORDER BY COALESCE(c.ParentId, c.Id), Timestamp DESC
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1 Answer

  1. Editorial Team

    I think that this query returns rows in the order that you want:

    SELECT c.*
FROM Comments c
ORDER BY
  COALESCE(ParentID, ID) DESC,
  ParentID is not null,
  Timestamp DESC

    It orders rows in descending order by ParentID if it is not null, otherwise by ID, then rows with null go at the top, and then by timestamp desc.

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