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;