I am trying to find out the number of users who have scored an average of 80 or higher. I am using Having in my query but it is not returning the count of number of rows.
The Schema looks like:
user
test_no
question_no
score
My Query:
SELECT "user" FROM results WHERE (score >0) GROUP BY "user"
HAVING (sum(score) / count(distinct(test_no))) >= 80;
I get:
user
2
4
8
(3 rows)
Instead I would like to get 3 (number of rows) as the output. If I do count("user"), I get the count of number of tests for each user.
I understand this is related to use Group By but I need it for my Having clause. Any suggestions how I can do this is appreciated.
Update: Here is some sample data: http://pastebin.com/k1nH5Wzh (-1 means unanswered)
Thanks!
The query you found is good. Some minor simplifications:
SELECT count(*) AS ct
FROM (
SELECT 1
FROM result
WHERE score > 0
GROUP BY user_id
HAVING (sum(score) / count(DISTINCT test_no)) >= 80
) sub
DISTINCT does not require parentheses.
You can SELECT a constant value in the subquery. The value is irrelevant, since you are only going to count the rows. Slightly shorter and cheaper.
Don't use the reserved word user as column name. That's asking for trouble. I am using user_id instead.
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