create table #orderbytest (a char(1), b int)

insert #orderbytest
select
    char((n%26) + 97),
    floor(rand(cast(newid() as varbinary(4))) * 1000000)
from
    numbers -- (FYI - create table numbers (n int) and fill with 1 thru 10000)
go

declare @orderby char(1)
set @orderby = 'b'

select
    a,
    b
from
    #orderbytest
order by
    case
        when @orderby = 'a' then a
        when @orderby = 'b' then b
    end ASC

quote:

---

Server: Msg 245, Level 16, State 1, Line 4
Syntax error converting the varchar value 'a' to a column of data type int.

---