Actual table:
ID Oc_date marks
1 25-Jul-15 10
2 26-Jul-15 10
3 27-Jul-15 10
4 28-Jul-15 10
5 29-Jul-15 10
Required result:
1 25-Jul-15 10
2 26-Jul-15 20
3 27-Jul-15 30
4 28-Jul-15 40
5 29-Jul-15 50
Need a simple query to get this output.