Question

I have a column of numbers in a MySQL database, along with a timestamp column and other stuff. I want to know the average of all of the values within a set parameter (say, within the last week), and I also want the average of all of the values that are >= X during that same timeframe. So, if my X is 10, and my values are:
0 0 10 15 20, then I want avg = 9 and avg2 = 15. One way I can do this is run two separate queries, with and without WHERE val >= 10, but I’d like to do it in just one query, if possible. Is there a way of doing this? I’ve looked at using a CASE, but I can’t get the syntax right. Below is the query that I tried:

SELECT AVG(watts), AVG(CASE watts WHEN watts >= 10 THEN watts END CASE) FROM power WHERE meterID = 100 AND time >= '2010-07-29 00:00:00'

Edit: This is what I ended up with.

SELECT AVG(watts) AS avg1,
AVG(IF (watts >= 10, watts, NULL)) AS avg2
FROM power
WHERE meterID = 100 AND time >= '2010-07-30 00:00:00'

Answer 1

SELECT
   AVG(watts),
   SUM(IF(watts>10,watts,0))/SUM(IF(watts>10,1,0))
FROM FOO
WHERE
   meterID   = 100 and
   time      >= '2010-07-29 00:00:00'

Version 2

SELECT
 AVG(watts),
 IF(SUM(IF(watts>10,1,0))=0,NULL,SUM(IF(watts>10,watts,0))/SUM(IF(watts>10,1,0)))
FROM FOO
WHERE
   meterID   = 100 and
   time      >= '2010-07-29 00:00:00'