How to select values by groups, using select sum()? - mysql

Question

I need to select values by groups (from 0 to 10, from 10 to 50, more than 50).
user_id amount
1 20
1 40
2 5
3 30
3 1
Why this query doesn't work correctly?
select (select sum(amount)),
case
when (select sum(amount))<10 then '0-10'
when (select sum(amount))>=10 and (select sum(amount))<50 then '10-20'
else '>50' end as total_amount, count(distinct user_id)
from table
group by
case
when (select sum(amount))<10 then '0-10'
when (select sum(amount))>=10 and (select sum(amount))<50 then '10-20'
else '>50' end as total_amount, count(distinct user_id);
output
diapason number_of_users
0-10 1
10-50 1
>50 1
Give me hint plz

Answer 1

Your query has a number of issues, but primarily it will not work because you need to do the sum by user prior to the sorting into ranges. Try this instead:
SELECT CASE
WHEN amount BETWEEN 0 AND 9 THEN ' 0-10'
WHEN amount BETWEEN 10 AND 50 THEN '10-50'
ELSE '>50' END AS diapason,
COUNT(*) AS number_of_users
FROM (SELECT SUM(amount) AS amount
FROM payments
GROUP BY user_id) p
GROUP BY diapason;
Output
diapason number_of_users
0-10 1
10-50 1
>50 1

Answer 2

Try below way
select
sum(case when amount <10 then 1 else 0 end) as "0-10",
sum(case when amount >=10 and amount <50 then 1 else 0 end) as "0-50" , sum(case when amount>50 then 1 else 0 end) as ">50"
from table

Answer 3

Your syntax is incorrect:
select case
when amount<10 then '0-10'
when samount>=10 and amount<50 then '10-20'
else '>50' end as total_amount, count(distinct user_id)
from table
group by
case
when amount<10 then '0-10'
when samount>=10 and amount<50 then '10-20'
else '>50' end

Answer 4

You can try this, writting a subquery get SUM of amount by each user_id, then do CASE WHEN, you don't need select sum(amount) in CASE WHEN.
CREATE TABLE t(
user_id int,
amount int
);
insert into t values(1,20);
insert into t values(1,40);
insert into t values(2,5);
insert into t values(3,30);
insert into t values(3,1);
Query 1:
select
case
when t1.total<10 then '0-10'
when t1.total>=10 and t1.total<50 then '10-50'
else '>50' end as diapason,
count(distinct user_id) number_of_users
from (
SELECT user_id,SUM(amount) total
FROM table
GROUP BY user_id
) t1
group by
case
when t1.total<10 then '0-10'
when t1.total>=10 and t1.total<50 then '10-50'
else '>50' end
Results:
| diapason | number_of_users |
|----------|-----------------|
| 0-10 | 1 |
| 10-50 | 1 |
| >50 | 1 |