help on query

hi guys

I have data in an internal table data like this below

A B C D

1 2 3 15

1 2 3 20

1 2 3 15

2 3 4 10

3 4 5 15

3 4 5 20

i want to compare three fields(A,B & c) if they are same i have to add the d and give a single result like below

A B C D

1 2 3 45

2 3 4 10

3 4 5 35

How can i handle this in coding?

Regards

senthil