Thank you for this tip with the STUFF function.

Is the order by in the subquery really needed? I think the for xml does it anyways. If you don't use the order by; you may use distinct to get every value only once.

WITH CTE AS

(

SELECT DISTINCT

AccountNumber

FROM #TestData

)

SELECT AccountNumber,

CommaList = STUFF((

SELECT distinct ',' + Value --<<-- to get every value only once

FROM #TestData

WHERE AccountNumber = CTE.AccountNumber

--ORDER BY Value --<<--

FOR XML PATH(''),

TYPE).value('.','varchar(max)'),1,1,'')

FROM CTE

ORDER BY AccountNumber;

greetings Reto E.