ai_no_kareshi wrote:

> Greetings, all. Suppose I have a table of time periods which I want to
> order by their length. I am trying to do something like the following,
> which I know does not work:
>
> SELECT P.PeriodName, (P.EndDate - P.StartDate) AS PeriodLength
> FROM Periods P
> ORDER BY 2 DESC
>

Works for me.
Which version do you use?

--
Magnus