SQL Server 2012, doubts

Question

Based on the attached table, could you tell me if the resolution of the exercise below is correct?

Show orders that have items that were sold at a discount (discount occurs when the sale price - Ite_precounitario - is lower than the price of "table" - Pro_preco).

My resolution:

select p.ped_numero, ite_precounitario, pro_preco
from pedido p, item i, produto pr
where p.ped_numero = i.ped_numero 
and i.pro_codigo = pr.pro_codigo
and ite_precounitario < pro_preco

Answer 1

Yes, but I would put all the prefixes to avoid ambiguities:

select p.ped_numero, i.ite_precounitario, pr.pro_preco
from pedido p, item i, produto pr
where p.ped_numero = i.ped_numero 
and i.pro_codigo = pr.pro_codigo
and i.ite_precounitario < pr.pro_preco

It would also go to the ANSI syntax, which is more readable:

select p.ped_numero, i.ite_precounitario, pr.pro_preco
from pedido p
    inner join item i on p.ped_numero = i.ped_numero 
    inner join produto pr on i.pro_codigo = pr.pro_codigo
where i.ite_precounitario < pr.pro_preco