How to create second column by adding the values in first column in SQL?

Question

Below given table ABC has column Num and second column should be created by adding the values in column first. Table ABC

Num
1
2
3
4
5

Output

Num  Num2
1    1
2    3
3    6
4    9
5    12

Answer 1

Oracle supports the ANSI standard method of calculating cumulative sums:

select num, sum(num) over (order by num)
from t;

Answer 2

And you can do this in MYSQL

SELECT    T.* ,
             @SUM:=@SUM + T.num AS RunningTotal
FROM     (SELECT @SUM:=0) S,T