[GENERAL] IN clause

[surabhi.ahuja]

Hi,
 
i have a table 
and i have the query select * from table where col_name is null;
 
it returns some rows
 
now, say i have to implement the same query using the in clause how shold it be 
done?
 
select * from table where col_name in (null);
 
but it does not return any rows.
 
Can you please suggest some way of doing it?
 
thanks,
regards
Surabhi