Question

I want to have a computed column that is true if the field asofdate is equal to the maximum asofdate in the table, otherwise false. I tried the following but I am getting a syntax error. What is the right way to do this?

select 
case asofdate
when select max(asofdate) from sometable then 1
else 0
end 
from sometable

Alternatively, is it possible to have a computed column along the lines of

case asofdate
when END OF PREVIOUS MONTH then 1
else 0
end

Answer 1

You cannot do it in an computed column, since the computed column can be only computed from the values of other columns in the same record.

You can do it in a view, instead:

CREATE VIEW
        v_with_last
AS
SELECT  *, CASE asofdate WHEN MAX(asofdate) OVER () THEN 1 ELSE 0 END AS the_last
FROM    sometable

Unfortunately, you cannot index this view.