Select query using varchar with 'in' - sql-server

Question

I have this query:
DECLARE #holdIds VARCHAR(MAX)
SET #holdIds = '1,2,3'
DECLARE #flagNames NVARCHAR(MAX);
SELECT
#flagNames = COALESCE(#flagNames + ',', '') + FlagName
FROM
BurnHoldStatus
WHERE
BurnHoldStatusID in (#holdIds);
SELECT #flagNames AS FlagName;
In this example the variable '#holdIds' has values '1,2,3' but could have just one value '1'.
When I run the query, an error appears:
Msg 245, Level 16, State 1, Line 6
Conversion failed when converting the varchar value '1,2,3' to data type int.
I try convert the value of '#holdIds' but not work.
Any idea?
Thanks.
[UPDATE]
I found the answer:
DECLARE #holdIds NVARCHAR(MAX);
SET #holdIds = '1,2,3';
DECLARE #holdIdList TABLE(id INT);
INSERT INTO #holdIdList
SELECT * FROM Split(#holdIds, ',');
DECLARE #flagNames NVARCHAR(MAX);
SELECT
#flagNames = COALESCE(#flagNames + ',', '') + FlagName
FROM
BurnHoldStatus, #holdIdList h
WHERE
BurnHoldStatusID = h.id;
SELECT #flagNames AS FlagName;
In this code I use an function 'Split' to split a string passing the divisor (i.e: ',').
Split function code:
ALTER FUNCTION [dbo].[Split]
(
#RowData nvarchar(MAX),
#SplitOn nvarchar(MAX)
)
RETURNS #RtnValue table
(
Data nvarchar(MAX)
)
AS
BEGIN
Declare #Cnt int
Set #Cnt = 1
While (Charindex(#SplitOn,#RowData)>0)
Begin
Insert Into #RtnValue (data)
Select
Data = ltrim(rtrim(Substring(#RowData,1,Charindex(#SplitOn,#RowData)-1)))
Set #RowData = Substring(#RowData,Charindex(#SplitOn,#RowData)+1,len(#RowData))
Set #Cnt = #Cnt + 1
End
Insert Into #RtnValue (data)
Select Data = ltrim(rtrim(#RowData))
Return
END
Thanks for Vercelli by show other post.
Thanks guys :)

Answer 1

The comment made by swe is correct. You could make the query dynamic, then insert #holdIds See below for a workaround:
DECLARE #holdIds VARCHAR(MAX)
SET #holdIds = '1,2,3'
SET #holdIds = (CHAR(39) + (REPLACE(#holdIds, ',', ''',''') + CHAR(39)))
You can do this, then set the entire query above as a varchar variable, then execute. There are certainly other workarounds as well but dynamic SQL will work.