如何为 SQL 服务器中的多个列使用 stuff 函数？

您可以执行以下操作。只需按这些列分组，并为串联列进行 2 个子选择：

select UserID, 
       ConductedByID, 
       QuestionID, 

       (SELECT STUFF((SELECT ';' + Response
                      FROM TableName tn2 WHERE tn1.UserID = tn2.UserID and 
                                     tn1.ConductedByID = tn2.ConductedByID and
                                     tn1.QuestionID = tn2.QuestionID and 
                                     tn1.ParticipantID = tn2.ParticipantID
            FOR XML PATH('')) ,1,1,'')) as Response,

       (SELECT STUFF((SELECT ';' + cast(Rating as varchar)
                      FROM TableName tn2 WHERE tn1.UserID = tn2.UserID and 
                                     tn1.ConductedByID = tn2.ConductedByID and
                                     tn1.QuestionID = tn2.QuestionID and 
                                     tn1.ParticipantID = tn2.ParticipantID
            FOR XML PATH('')) ,1,1,'')) as [Response Rating],

       AVG(case when Rating = 'n/a' then 0 else cast(Rating as int) end) as [Rating Avg], 
       ParticipantID
from TableName tn1
group by UserID, ConductedByID, QuestionID, ParticipantID