Chapter 4 set operation

Q1

select * from product where sale_price > 500
union
select * from product2 where sale_price > 500;

Q2

select * from (select * from product union select * from product2) as u
	where product_id not in (
select product_id from product where product_id not in (select product_id from product2)
union
select product_id from product2 where product_id not in (select product_id from product));

Q3

select sp.shop_id, sp.shop_name, sp.quantity,
        p.product_id, p.product_name, p.product_type, p.sale_price,
        mp.maxp as ' The maximum selling price of this kind of goods ' 
from product as p 
inner join shopproduct as sp 
on sp.product_id = p.product_id
inner join (
			select product_type, max(sale_price) as maxp from product 
            group by product_type
            ) as mp
on mp.product_type = p.product_type and p.sale_price = mp.maxp;

Q4

select p.product_id, p.product_name, p.product_type, p.sale_price
from product as p 
inner join (
			select product_type, max(sale_price) as maxp from product 
            group by product_type
            ) as mp
on mp.product_type = p.product_type and p.sale_price = mp.maxp;

Q5

select p.product_id, p.product_name, p.product_type, p.sale_price,
	(select sum(sale_price) from product as p1
	where p.sale_price > p1.sale_price
	or (p.sale_price = p1.sale_price and p.product_id >= p1.product_id)
	) as ' Cumulative sum '
from product as p 
order by sale_price;