Zadanie 1

Select * from orders where year(order_date)=1996;

Zadanie 2

Select name from Salesperson where len(name)=3;

Zadanie 3

select Salesperson.Name from Salesperson, Orders where 
Salesperson.ID = Orders.salesperson_id and cust_id = '4';

Zadanie 4

select Salesperson.Name from Salesperson 
where Salesperson.ID NOT IN(
select Orders.salesperson_id from Orders, Customer 
where Orders.cust_id = Customer.ID 
and Customer.Name = 'Samsonic');

Zadanie 5

SELECT name
FROM salesperson
WHERE age = (select TOP(1) age from salesperson where name like 'M%' order by name asc);

Zadanie 6

Select a.name as Osoba, count(*) as Liczba from (
SELECT Salesperson.name, Salesperson.id, count(*) as liczba
FROM Orders join Salesperson on  Orders.Salesperson_id = Salesperson.id
JOIN customer on customer.id = Orders.Cust_id
GROUP BY Customer.ID, salesperson.ID, salesperson.name
) a
group by a.id, a.name

Zadanie 7

SELECT name
FROM Orders, Salesperson
WHERE Orders.salesperson_id = Salesperson.id
GROUP BY name, salesperson_id
HAVING COUNT( salesperson_id ) = (SELECT TOP(1) count(*)as liczba
FROM Orders, Salesperson
WHERE Orders.salesperson_id = Salesperson.id
GROUP BY name, salesperson_id
order by liczba desc)