You could use Phil's suggested query as a subquery. This lets you add as many CASE statements with as many WHEN statements as you want and it lets you filter out those unwanted columns in the final query result. The following code should give you an idea of what I mean. Obviously the OrderBy2 part would not have the same syntax as OrderBy1.

SELECT

sub.VacancyInternalID

,sub.VacancyTitle

,sub.ParentInternalID

,sub.GeoLocation

FROM

(

select distinct VacancyInternalID

,VacancyTitle

,null ParentInternalID

,null GeoLocation

,OrderBy1= (

case @SortFieldIndexConfig

when 1then VacancyInternalID

when 2then VacancyTitle

else VacancyInternalID

end

)

,OrderBy2= (

case @SortFieldIndexConfig

when 1then VacancyInternalID

when 2then VacancyTitle

else VacancyInternalID

end

)

from Vacancy.TB_Vacancy va

inner join Config.TB_Contract co on va.VacancyContractID = co.ContractInternalID

where co.ContractExternalID = '492A94D0-7D71-46E5-A8F6-E3A973394647'

and co.ContractStatusID = 1

and VacancyStatusID = 1

and VacancyTitle like '%%'

) sub

ORDER BY sub.OrderBy1 DESC, sub.OrderBy2 DESC