Is there a way in one SQL to obtain a calculated field based on an expression field?

The following shows SumRate/TotRate in the SQL syntax. However, this doesn't work as the fields don't exist. How can I reformulate that line to make it work?

SELECT TOP 100 SUM(RATE) AS SumRate,COUNT(*) AS TotRate,SumRate/TotRate AS RATING,NOENTRY FROM RATING;
 WHERE NOCONTENT=tnNoContent GROUP BY NOENTRY ORDER BY RATING DESCENDING INTO CURSOR RatingTemp