value of column depends on to all previous values

Question

I am struggling to calculate a column (c3) when querying my table. in fact the value of c3 for a current row is depend on all previous value of the (c3).

for example the value of c3 of raw 3 will depend on c3 of raw2 and this latter is depended on c3 of raw1, and so on ...

| c1 |   c2  |    c3    | 
|----|-------|----------|
| 1  |   1   |          |<-- row1 
| 2  |   6   |          |<-- row2
| 3  |   2   |          |<-- row3
| 4  |  10   |          |<-- row4

• for row1: the value of c3 = 1 + 1 which gives 2
• for row2: the value of c3 = (2) + 2 + 6 which gives 10
• for row3: the value of c3 = (10) + 3 + 2 which gives 15
• for row4: the value of c3 = (15) + 4 + 10 which gives 29

how could I write my query.

Answer 1

That's a window sum. Assuming that column c1 defines the ordering of the rows, that would be:

select
    c1,
    c2,
    sum(c1 + c2) over(order by c1) c3
from mytable