Order by & case

I am trying to use a case statment to indicate sort order. Everything worked fine untill I added "desc".

create table #tmp(f1 varchar(25), dtObs datetime, dtCnt datetime)
insert into #tmp values('ABC','01-Jan-2003','02-Jan-2003')
insert into #tmp values('BCD','01-Jan-2003','03-Jan-2003')
insert into #tmp values('CDE','01-Jan-2003','04-Jan-2003')
insert into #tmp values('DEF','02-Jan-2003','03-Jan-2003')
insert into #tmp values('EFG','02-Jan-2003','04-Jan-2003')
insert into #tmp values('FGH','02-Jan-2003','05-Jan-2003')

declare @.Order tinyint
set @.Order = 1
select *
from #tmp
order by case @.Order when 1 then 'dtObs'
when 2 then 'dtCnt'
when 3 then 'dtObs desc'
when 4 then 'dtCnt desc'
else null end

any suggestion on how to do this?select *
from #tmp
order by case @.Order when 1 then 'dtObs'
when 2 then 'dtCnt'
else null end
,case @.Order when 3 then 'dtObs'
when 4 then 'dtCnt'
else null end DESC|||Thanks!|||Pleasure to help you.|||I am using a Case statement within my Order By clause, but I have columns that I want to use that were created in my Select clause as expressions. I cannot seem to use those columns in my Case statement. Is there a way to do this?? Thank you very much for your help!!!sql