A recent thread made me question which way of doing the same thing is the "better" way. I'd like to know which is least demanding on the processor. I've pasted the queries and the results below, but it's basically an expression field containing a DMax() function or an expression field with a nested Select Max() statement. From behavior, I guess the nested select is more versatile because you can include a WHERE clause, but the DMax() resultset has the advantage of still being able to append new records. That's nice and all, but I'm wondering which executes faster.
Does the processor really have to run every single row against its own DMax() or nested Select? Can't the "brain" of the database first solve for the Max value only one time, and then remember that value for use in each row of the expression field?