How to display minimum values from group?

Question

Hi Friends,

my table is:

create table tab

(

ref_group,

product,

qty

)

insert into tab(ref_group,product,qty)

values ('Milk Produtcs','Curd','25')

insert into tab(ref_group,product,qty)

values ('Milk Produtcs','Butter','05')

My expecting O/P:

groupProduct           product                  sales         free

Milk Products           Butter                       0               05

here i wanna show lowest product value from group how to make a code?