Currently I have the following query in TSQL:

select *
from table
order by
    col1, col2

But there’s a condition (@cond = 1), which if it is true, then I should rather sort by column col0 DESC and then use the rest:

select *
from table
order by
    case when @cond = 1 then col0 end DESC,
    col1,
    col2

which works fine when the condition is true. But if it’s false, then I have an error message (in that case I want to have the initial query).

How to make the trick here?