Execution order of functions in MySQL

Question

I am aware that the execution order of MySQL is not fixed. But, I heard it usually goes like this:

1. FROM, including JOINs
2. WHERE
3. GROUP BY
4. HAVING
5. SELECT
6. DISTINCT
7. ORDER BY
8. LIMIT and OFFSET

However, if I run functions like COUNT() for example (like the code below), when does it get to be executed? and how does MySQL decide the subjects that will be calculated with the function (e.g. What to count for COUNT() function)? I am confused about the execution order and the target designation of functions like AVG(), SUM(), MAX(), etc. in MySQL.

SELECT productvendor, count(*)
FROM products
GROUP BY productvendor
HAVING count(*) >= 9;

Answer 1

You sequence is not correct
select is before GROUP BY

FROM, including JOINs
WHERE
SELECT the row  obtained  by from and where in a temporary area for others 
        operation (and build the column alias)
DISTINCT
GROUP BY
HAVING
ORDER BY
LIMIT and OFFSET
return the final result 

the count and the aggegation function are done on a temporary result with the select column .. this operation produce the result filtered by having