@Formula("(select STUFF( (Select ','+ s.groupName From table_a as s Where deny_crlevel like '%'s.groupCode'%' For XML PATH ('') ),1,1,''))")

The sql translated as
...
.deny_crlevel like '%'s.groupCode'%' this_.For this_.XML this_.PATH ('') ),1,1,'')) as formula0_0_ from CHK_ResvRule this_
...