MySQL Query: Invalid column vs Invalid use of Group Function. Help!

[acidbox]

I have an SQL statement as follows:

SELECT x.xreport_id, MIN(xd.xd_worked) as date_from, MAX(xd.xd_worked) as date_to FROM xreports x, xreport_detail xd WHERE xd.xreport_id = x.xreport_id AND TO_DAYS('2005-02-02') - TO_DAYS(date_from) >= 0 AND TO_DAYS('2005-02-14') - TO_DAYS(date_to) <= 0 GROUP BY x.xreport_id ORDER BY date_from DESC

If i do this version, it says Unknown column 'date_from' in 'where clause'. I understand that date_from and date_to are not columns, but I thought it would recognize them because i created them with the AS feature due to the fact that the original value is a calculation..

Then, I tried this:

SELECT x.xreport_id, MIN(xd.xd_worked) as date_from, MAX(xd.xd_worked) as date_to FROM xreports x, xreport_detail xd WHERE xd.xreport_id = x.xreport_id AND TO_DAYS('2005-02-02') - TO_DAYS(MIN(xd.xd_worked)) >= 0 AND TO_DAYS('2005-02-14') - TO_DAYS(MAX(xd.xd_worked)) <= 0 GROUP BY x.xreport_id ORDER BY date_from DESC

Now if I replace "date_from" and "date_to" with the actual computation (ie: MAX() and MIN() ), I get this: Invalid use of group function.

How can I get the TO_DAYS to use the MAX or MIN value that I am creating?

Thanks in advance...

[Lars_Berg]

aggregates can be used in having clause

having 
TO_DAYS('2005-02-02') - TO_DAYS(MIN(xd.xd_worked)) >= 0
-- etc

[acidbox]

Oh cool, I wasn't aware that HAVING existed. I assume you can use WHERE and HAVING in the same statement, yes?

Thanks again!