How to add a few restrictios to a query? - mysql

Question

I have difficulty with syntax...
This is my query:
SELECT t.diapason,
Count(*) AS 'number_of_users'
FROM (SELECT CASE
WHEN amount < 200 THEN '0-200'
WHEN amount >= 200 THEN '200 +'
end AS diapason
FROM (SELECT Sum(amount) AS amount
FROM payments) p) t
GROUP BY t.diapason
ORDER BY number_of_users DESC;
But now I need to select only users which had activity.login_time between '2018-01-01' and'2018-01-12'.
So, I think I should use INNER JOIN and set period of time. Bu how?
My tables:
activity
user_id login_time
1 01.01.2018
2 01.01.2018
3 03.01.2018
4 30.02.2018
payments
user_id amount payment_time
1 50 10.12.2017
1 200 09.12.2017
2 40 08.08.2017
what should I change in my query to add activity.login_time?
Output for period 01.01.2018-12.01.2018
diapason number_of_users
0-200 2
200+ 1

Answer 1

I understand your question as this. You had 3 users (user_id=1,2,3) login in the period 01.01.2018-12.01.2018. Of those users, user_id 1 made 2 payments totalling 250, user_id 2 made 1 payment of 40, and user_id 3 made 0 payments so their total is 0. Hence there are 2 values in the range 0-200, and 1 in the range 200 +. If that is the correct understanding, this query will give you the desired results:
SELECT CASE
WHEN amount < 200 THEN '0-200'
WHEN amount >= 200 THEN '200 +'
END AS diapason,
COUNT(*) AS number_of_users
FROM (SELECT a.user_id, COALESCE(SUM(p.amount), 0) AS amount
FROM activity a
LEFT JOIN payments p ON p.user_id = a.user_id
WHERE a.login_time BETWEEN '01.01.2018' AND '12.01.2018'
GROUP BY a.user_id) p
GROUP BY diapason;
Output:
diapason number_of_users
0-200 2
200 + 1
SQLFiddle demo
Update
To add another row with the total number_of_users, just add WITH ROLLUP to the GROUP BY clause:
SELECT CASE
WHEN amount < 200 THEN '0-200'
WHEN amount >= 200 THEN '200 +'
END AS diapason,
COUNT(*) AS number_of_users
FROM (SELECT a.user_id, COALESCE(SUM(p.amount), 0) AS amount
FROM activity a
LEFT JOIN payments p ON p.user_id = a.user_id
WHERE a.login_time BETWEEN '01.01.2018' AND '12.01.2018'
GROUP BY a.user_id) p
GROUP BY diapason WITH ROLLUP
Output:
diapason number_of_users
0-200 2
200 + 1
(null) 3
In your application framework you can use the fact that the diapason value is NULL to output something like Total instead.
Updated SQLFiddle
You can also do the same in MySQL (see this SQLFiddle) by wrapping this query up as a subquery and using a COALESCE on the diapason column. In that case the output would be:
diapason number_of_users
0-200 2
200 + 1
Total 3

Answer 2

You add WHERE clause to filter.
SELECT t.diapason,
COUNT(*) AS 'number_of_users'
FROM (
SELECT
CASE
WHEN amount < 200 THEN '0-200'
WHEN amount >= 200 THEN '200 +'
END AS diapason
FROM (
SELECT payments.user_id, SUM(amount) AS amount
FROM payments
INNER JOIN activity ON payments.user_id = activity.user_idAND activity.login_time = payments.payment_time
WHERE activity.login_time BETWEEN '2018-01-10' AND '2018-01-12'
GROUP BY payments.user_id
) p
) t
GROUP BY t.diapason
ORDER BY number_of_users DESC;