How to use Group By with where condition to concatenate column value in SQL Server - sql

Question

I want to return asset count as per type and also want to concatenate asset ids. I am using FOR XML and path which works fairly good but as soon as I add where clause, it does not work as expected.
This is my table schema and query:
CREATE TABLE [dbo].[Asset]
(
[AssetSeqNumber] [bigint] NULL,
[AssetType] [varchar](100) NULL
) ON [PRIMARY]
GO
INSERT [dbo].[Asset] ([AssetSeqNumber], [AssetType])
VALUES (1, N'Tree')
INSERT [dbo].[Asset] ([AssetSeqNumber], [AssetType])
VALUES (2, N'Tree')
INSERT [dbo].[Asset] ([AssetSeqNumber], [AssetType])
VALUES (3, N'Tree')
INSERT [dbo].[Asset] ([AssetSeqNumber], [AssetType])
VALUES (4, N'Barbecue')
INSERT [dbo].[Asset] ([AssetSeqNumber], [AssetType])
VALUES (5, N'Bridge')
INSERT [dbo].[Asset] ([AssetSeqNumber], [AssetType])
VALUES (101, N'Tree')
INSERT [dbo].[Asset] ([AssetSeqNumber], [AssetType])
VALUES (102, N'Tree')
GO
Query:
SELECT
AssetType,
COUNT(AssetSeqNumber) AS count,
STUFF((SELECT DISTINCT ',' + CAST(AssetSeqNumber AS varchar(100))
FROM Asset
WHERE AssetType = a.AssetType
FOR XML PATH ('')), 1, 1, '') AS AssetIds
FROM
Asset AS a
WHERE
a.AssetSeqNumber IN (1, 2, 3, 4, 5)
GROUP BY
AssetType
This query return result for ids which are not in the where condition (i.e. 101,102). I understand it is because inner query check asset types but I can't figure out how to show expected result.
Note: I am using SQL Server 2019 (v15.0.2095.3 (X64))

Answer 1

You need to modify the where clause for the select statement inside the STUFF function as the following:
WHERE AssetType = a.AssetType AND AssetSeqNumber IN (1, 2, 3, 4, 5)
Also, for your version of SQL Server, you could simplify this by using STRING_AGG function as the following:
SELECT AssetType,
COUNT(*) [Count],
STRING_AGG(AssetSeqNumber, ',') AssetIds
FROM Asset
WHERE AssetSeqNumber IN (1, 2, 3, 4, 5)
GROUP BY AssetType
See a demo for both queries.

Answer 2

your data
drop table if exists #Asset
CREATE TABLE #Asset
(
[AssetSeqNumber] [bigint] NULL,
[AssetType] [varchar](100) NULL
) ON [PRIMARY]
GO
INSERT #Asset ([AssetSeqNumber], [AssetType])
VALUES (1, N'Tree')
INSERT #Asset ([AssetSeqNumber], [AssetType])
VALUES (2, N'Tree')
INSERT #Asset ([AssetSeqNumber], [AssetType])
VALUES (3, N'Tree')
INSERT #Asset ([AssetSeqNumber], [AssetType])
VALUES (4, N'Barbecue')
INSERT #Asset ([AssetSeqNumber], [AssetType])
VALUES (5, N'Bridge')
INSERT #Asset ([AssetSeqNumber], [AssetType])
VALUES (101, N'Tree')
INSERT #Asset ([AssetSeqNumber], [AssetType])
VALUES (102, N'Tree')
GO
you should add your condition into your Xml query
SELECT
AssetType,
COUNT(AssetSeqNumber) AS count,
STUFF((SELECT DISTINCT ',' + CAST(AssetSeqNumber AS varchar(100))
FROM #Asset
WHERE AssetType = a.AssetType /*yourcondition*/and AssetSeqNumber IN (1, 2, 3, 4, 5)
FOR XML PATH ('')), 1, 1, '') AS AssetIds
FROM
#Asset AS a
WHERE
a.AssetSeqNumber IN (1, 2, 3, 4, 5)
GROUP BY
AssetType
by consider using SQL Server 2019,you can use string_agg
SELECT [assettype],
Count(assetseqnumber) count,
String_agg(assetseqnumber, ',') AssetIds
FROM #asset a
WHERE a.assetseqnumber IN ( 1, 2, 3, 4, 5 )
GROUP BY [assettype]