FILAS EN UNA SOLA COLUMNA, SQL-T

WITH ORDERS

 AS

 (

 select OrderId = 1,ProductId = 100

 union select 1,158

 union select 1,234

 union select 2,125

 union select 3,105

 union select 3,101

 union select 3,212

 union select 3,250

 )

 select distinct

       orderid

   ,REPLACE(LTRIM(REPLACE((  SELECT ' ' + CAST(ProductId as varchar)

       FROM ORDERS d

       WHERE d.OrderId = o.OrderId

       FOR XML PATH('')

   ),' ','')),' ', ', ') as Products

 from ORDERS o

RESULTADO: