Trying to compare multiple implementations of dynamic ordering in sql server

sql-server-row-number-performance.sql

create table #test_data(col1 varchar(100), col2 varchar(100))

declare @i int = 0 
while (@i < 1000000)
begin 
	insert into #test_data(col1, col2) 
	values ('col1_' + right('00000000' + cast(@i as varchar(9)), 9), CONVERT(varchar(255), NEWID()))

	set @i = @i + 1
end


declare @ordering_field int  = 0
declare @descending bit  = 1
 
set @ordering_field = 1
set @descending = 0

select top 100 
	ROW_NUMBER() OVER (ORDER BY case when @ordering_field = 1 then col1 else col2 end) * (1 - 2*@descending) rownumber, * 
from #test_data
order by rownumber

set @ordering_field = 1
set @descending = 1

select top 100 
	ROW_NUMBER() OVER (ORDER BY case when @ordering_field = 1 then col1 else col2 end) * (1 - 2*@descending) rownumber, * 
from #test_data
order by rownumber

set @ordering_field = 0
set @descending = 0

select top 100 * 
from #test_data
order by 
	case when @descending = 1 then  
		case when @ordering_field = 1 then col1 else col2 end
	end, 
	case when @descending = 0 then 
		case when @ordering_field = 1 then col1 else col2 end 
	end desc

set @ordering_field = 0
set @descending = 0

select top 100 * 
from #test_data
order by 
	case when @descending = 1 then  
		case when @ordering_field = 1 then col1 else col2 end
	end, 
	case when @descending = 0 then 
		case when @ordering_field = 1 then col1 else col2 end 
	end desc

set @ordering_field = 1
set @descending = 1

select top 100 *
from
	(select ROW_NUMBER() OVER (order by col1) rownumber_col1,
			ROW_NUMBER() OVER (order by col2) rownumber_col2, 
			* 
	from #test_data) t
order by 
	case when @ordering_field = 1 then rownumber_col1 
	else rownumber_col2 end


set @ordering_field = 0
set @descending = 0

select top 100 *
from
	(select ROW_NUMBER() OVER (order by col1) rownumber_col1,
			ROW_NUMBER() OVER (order by col2) rownumber_col2, 
			* 
	from #test_data) t
order by 
	case when @ordering_field = 1 then rownumber_col1 
	else rownumber_col2 end