>select max(column1 - ###) from table1
>
>How Can this be optimized? There is an index on column1. ### is a user selectable numeric value.

Since regardless of value, ### is a constant, and MAX() always returns a single row per grouping, you could optimize by:

SELECT MAX(column1) AS MaxColumn1 FROM Table1 INTO CURSOR TEMP
SELECT MaxColumn1 - ### AS Result FROM TEMP