Can I use aggregate functions?

[D]

I've find akshell just yesterday, really nice product!

Let's say I have the following table: (RelVar, set of tuples...)

Id | Num | CategoryID  

--------------------- 

a  | 2   | x

b  | 3   | y

c  | 5   | z

d  | 0   | x

e  | 4   | z 

f  | 2   | z

How could I get something like:

CategoryID | Count(*) | Sum(Num)

--------------------------------

x          | 2        | 2

y          | 1        | 3

z          | 3        | 11

Does it possible to use aggregate functions as in SQL, or should I fetch all data and then loop over it?