oracle - SQL: How to display a column not in group by expression? -

i have following code:

select o.ono customers c, odetails od, orders o, parts p p.pno=od.pno , od.ono=o.ono , o.cno=c.cno group o.ono order sum(od.qty*p.price)desc; 

however, instead of selecting o.ono column, need select c.cname different table. how go doing that?

if want list of customer names ordered sum of orders change query from

select o.ono ... group o.ono 

to

select c.cname ... group c.cname 

this display customer name , order number. note: repeat customer name many times there orders customer

also, preferred style of sql queries

select c.cname customers c     inner join orders o on c.cno = o.cno     inner join odetails od on o.ono = od.ono     inner join parts p on oid.pno = p.pno p.pno=od.pno , od.ono=o.ono , o.cno=c.cno group c.cname order sum(od.qty*p.price)desc; 

an additional suggestion clarify code. (please note: i'm not oracle person), in company (sqlserver) have table named after entity, primary key being id, , property named without prefix. instance oid refer orderid or officeid?

eg:

customer:

• id
• name

order:

• id
• customerid

then queries more readable:

select name customer     inner join order on customer.id = order.customerid ... order customer.name