can you pass a mysql column alias to a user defined function

Question

I have a select statement which displays a number of counts based on different criteria

I want to pass the counts to a user defined function (UDF) to do some calculations

e.g.

SELECT 
player, 
COUNT(IF(action=1,1,NULL)) AS tot_bullseye, 
COUNT(IF(action=2,1,NULL)) AS tot_twentys

UDF(tot_bullseye, tot_twentys)

Answer 1

No, column aliases can never be accessed in the SELECT or WHERE clause for the same query. You have to either repeat the expression, or use a subquery:

SELECT player, tot_bullseye, tot_twentys, UDF(tot_bullseye, tot_twentys)
FROM (SELECT player,
             COUNT(IF(action=1,1,NULL)) AS tot_bullseye,
             COUNT(IF(action=2,1,NULL)) AS tot_twentys
      ...) AS subq