Using GROUP BY with FOR XML PATH in SQL Server 2016 - sql

Question

I am trying to
group by ID and
aggregate multiple comments into a single row
Right now, I can do the no. 2 part for a single ID (ID = 1006), but I would like to aggregate comments for all IDs. I am struggling where and how to add "group by" clause in my query.
Here is the query:
create table Comments (ID int, Comment nvarchar(150), RegionCode int)
insert into Comments values (1006, 'I', 1)
, (1006, 'am', 1)
, (1006, 'good', 1)
, (1006, 'bad', 2)
, (2, 'You', 1)
, (2, 'are', 1)
, (2, 'awesome', 1)
SELECT
SUBSTRING((SELECT Comment
FROM Comments
WHERE ID = 1006 AND RegionCode != 2
FOR XML PATH('')), 1, 999999) AS Comment_Agg
My desired result looks something like this:
FYI, I am using FOR XML PATH here to aggregate multiple comments into a single row because STRING_AGG function is not supported in my version - SQL Server 2016 (v13.x).

Answer 1

Please try the following solution.
SQL
-- DDL and sample data population, start
DECLARE #tbl TABLE (ID int, Comment nvarchar(150));
INSERT INTO #tbl VALUES
(1006, 'I'),
(1006, 'am'),
(1006, 'good'),
(2, 'You'),
(2, 'are'),
(2, 'awesome');
-- DDL and sample data population, end
DECLARE #separator CHAR(1) = SPACE(1);
SELECT p.ID
, STUFF((SELECT #separator + Comment
FROM #tbl AS c
WHERE c.ID = p.ID
FOR XML PATH('')), 1, LEN(#separator), '') AS Result
FROM #tbl AS p
GROUP BY p.ID
ORDER BY p.ID;
Output
+------+-----------------+
| ID | Result |
+------+-----------------+
| 2 | You are awesome |
| 1006 | I am good |
+------+-----------------+