Creating a cumulative sum column in MySQL

Question

Sample table ID: (num is a key so there wouldn\'t be any duplicates)

num
1
5
6
8
2
3

Desired output:
(Should be sorted and have a cumul

Answer 1

You can use a temporary variable to calculate the cumulative sum:

SELECT  a.num,
   (@s := @s + a.num) AS cumulative
FROM ID a, (SELECT @s := 0) dm
ORDER BY a.num;

Answer 2

I think I figured out the solution.

Select num as n, 
       (select sum(num) from ID where num <= n)
from ID order by n;

Answer 3

as these answer i already tested in my project and actually i want to know which one is faster so i also posted this here which one is faster

declare @tmp table(ind int identity(1,1),col1 int)
insert into @tmp
select 2
union
select 4
union
select 7
union 

select 5
union
select 8
union 
select 10


 SELECT t1.col1,sum( t2.col1)
    FROM @tmp AS t1 LEFT JOIN @tmp t2 ON t1.ind>=t2.ind
    group by t1.ind,t1.col1

select t1.col1,(select sum(col1) from  @tmp as t2 where t2.ind<=t1.ind)
from @tmp as t1

Answer 4

Since MySQL 8, cumulative sums are ideally calculated using window functions. In your case, run:

SELECT num, SUM(num) OVER (ORDER BY num) cumulative
FROM id