You can use derived table. The execution plan most likely will be the same in both cases.

SELECT * FROM (  Select somefield+somethingelse as mycalcfield from mytable ) dt1
where mycalcfield>10

>In VFP you can do this
>
>Select somefield+somethingelse as mycalcfield from mytable where mycalcfield>10
>
>in T-SQL it seems you have to do this
>Select somefield+somethingelse as mycalcfield from mytable where somefield+somethingelse>10
>
>which means you have to maintain both calcfield expressions which is a maintenance headache
>
>Is there a way in T-SQL to use the calcfield alias in the where expression?