SQL & PL/SQL

Hello All,

I have a table the contains ID and size.

An ID identifies a unique object, but it can be repeated. The following is valid:

ID Size
-----------------
1 3
4 5
5 3
1 3


What I am trynig to do is get the sum of all sizes in the table. I tried this query:

select sum(distinct size) from table;

But it does give the right result since different objects could have the same size. I tried

select sum(size) group by ID;

But it prints to me huge number of IDs and sums the sizes of an ID together. What I want thuogh is to look at the unique rows (without duplicates) and then sum their sizes together and get the result.

Any help would be greatly appreciated.
Thank you

P.S.: Sorry, I am an absolute Oracle/SQl newbie.

Thanks for your help in advance