STUFF doesn't work well with NULL Values and Grouping - sql

Question

I have table with below schema and data.
CREATE TABLE [dbo].[SearchTest]
(
[DocumentNumber] [int] NOT NULL,
[AlphaNumeric] [nvarchar](50) NULL,
[Integers] [int] NULL
) ON [PRIMARY]
GO
INSERT [dbo].[SearchTest] ([DocumentNumber], [AlphaNumeric], [Integers])
VALUES (1, N'abc', 1)
INSERT [dbo].[SearchTest] ([DocumentNumber], [AlphaNumeric], [Integers])
VALUES (2, N'abc', 1)
INSERT [dbo].[SearchTest] ([DocumentNumber], [AlphaNumeric], [Integers])
VALUES (3, N'bcd', 2)
INSERT [dbo].[SearchTest] ([DocumentNumber], [AlphaNumeric], [Integers])
VALUES (4, N'bcd', 2)
GO
Table data:
I would like to do grouping using Alphanumeric and Integers column and get the DocumentNumber as comma separated value in my final result.
My final result should look like this,
Here is my query that gives the above output,
SELECT *
FROM
(SELECT
STUFF((SELECT ', ' + CAST(DocumentNumber AS VARCHAR(10)) [text()]
FROM SearchTest
WHERE AlphaNumeric = Result.Alphanumeric
OR Integers = Result.Integers
FOR XML PATH(''), TYPE).value('.', 'NVARCHAR(MAX)'), 1, 2, ' ') DocumentNumbers,
COUNT(DocumentNumber) TotalDocuments,
Result.AlphaNumeric,
Result.Integers
FROM
(SELECT *
FROM SearchTest
WHERE AlphaNumeric LIKE '%b%' OR Integers = 1) AS Result
GROUP BY
Result.AlphaNumeric, Result.Integers) AS Final
However the above query breaks if I have null values in Integers column.
For example, if I have NULL value in my integer columns as shown here:
Now my query breaks and I get the wrong results in my stuff query as shown below
Grouping works fine in the above query but STUFF part which gives DocumentNumbers gives wrong result. In this case it has be 2 in first row and 1 in second row.
Here is the expected result:
| DocumentNumbers| TotalDocuments| AlphaNumeric | Integers |
+----------------+---------------+---------------+---------------+
| 2 | 1 | abc | NULL |
| 1 | 1 | abc | 1 |
| 3, 4 | 2 | bcd | 2 |
Please assist on where I'm going wrong

Answer 1

You need to change the WHERE clause of the inner query to a) use AND instead of OR and b) to check for NULLs too.
SELECT stuff((SELECT concat(', ', documentnumber)
FROM searchtest st2
WHERE (st2.alphanumeric = st1.alphanumeric
OR st2.alphanumeric IS NULL
AND st1.alphanumeric IS NULL)
AND (st2.integers = st1.integers
OR st2.integers IS NULL
AND st1.integers IS NULL)
FOR XML PATH('')),
1,
2,
'') documentnumbers,
count(*) totaldocuments,
alphanumeric,
integers
FROM searchtest st1
WHERE st1.alphanumeric LIKE '%b%'
OR st1.integers = 1
GROUP BY st1.alphanumeric,
st1.integers;

Answer 2

Following #GordonLinoff comments in the question. This can be easily achieved using STRING_AGG() provided you're using SQL Server 2017 and above. This simplifies the query as well.
Query:
SELECT *
FROM
(SELECT
STRING_AGG(Result.DocumentNumber, ', ') DocumentNumbers,
COUNT(DocumentNumber) TotalDocuments,
Result.AlphaNumeric,
Result.Integers
FROM
(SELECT *
FROM SearchTest
WHERE AlphaNumeric LIKE '%b%' OR Integers = 1) AS Result
GROUP BY
Result.AlphaNumeric, Result.Integers) AS Final
Expected Output:

Answer 3

I had edited the code now:
You can use the below code to attain this:
SELECT S.DocumentNumbers,COUNT(S.DocumentNumbers) AS TotalDocuments,S.AlphaNumeric,S.Integers FROM
(SELECT COALESCE(Stuff((SELECT ', ' + CAST(DocumentNumber AS VARCHAR(10))
FROM SearchTest T1
WHERE T1.AlphaNumeric=T2.AlphaNumeric AND T1.Integers=T2.Integers
FOR XML PATH(''), TYPE).value('.','NVARCHAR(MAX)'),1,2,' ')
,CAST (T2.DocumentNumber AS VARCHAR(20))) AS DocumentNumbers,T2.AlphaNumeric,T2.Integers
FROM SearchTest T2) S
GROUP BY DocumentNumbers,S.AlphaNumeric,S.Integers
ORDER BY S.Integers