Giving a result with a sub query and a formula? - mysql

Question

I have this issue that is going around my head lately, I wanna know how many of my users can have more than a 50% of profit in their accounts. So, as you can see in the table, I have investment and earnings, so logically I must do a percentage for having the profit. Like: ((earnings - investment * 100) / investment)
ID Investment (euros) Earnings (euros)
13 2 3.4
14 1 0
15 4 7
16 12 20.76
From here everything is ok, but my question is, how can I calculate and show at the same time the users that have more than a 50% of profit?
I made this simple query that works but don't shows the users that have more than 50%, shows everyone.
select id, ((MAX(earnings)-investment)*100)/investment
from users
group by id, investment
;
So, my idea was to create a subquery, but I have a great issue with this:
select id
from users
where 50 < (
select (((MAX(earnings)-investment)*100)/investment)
from users
group by investment
)
group by id
;
I received this error:
Detail: Expected no more than one row to be returned by expression
I don't know what I'm doing wrong. Jalp!

Answer 1

Isn't this the formula?
select id, (sum(earnings) - sum(investment))*100 / sum(investment) as profit
from users
group by id;
Then if you want to filter, add:
having profit > 50
To get the count, use a subquery:
select count(*)
from (select id, (sum(earnings) - sum(investment))*100 / sum(investment) as profit
from users
group by id
) u
where profit > 50;