Varför inte prova på det här sättet
declare @Prefix2Include as Varchar(500)
SELECT @Prefix2Include = Prefix2Include FROM dbo.vw_PrefixToInclude
select * from dbo.fnSplit(@Prefix2Include , ',')
Uppdatera
Select * From @t v
Where v.EmpPrefix IN
(select * from dbo.fnSplit(@Prefix2Include, ','))