SET profiling = 1;
select sum(quantityOrdered * priceEach) as totalSales, city from 
orderdetails,
orders, 
(SELECT customerNumber,customerName, offices.city 
FROM customers,employees,offices
where customers.salesRepEmployeeNumber=employees.employeeNumber AND employees.officeCode=offices.officeCode
) as customerCity
where orderdetails.orderNumber=orders.orderNumber AND  
orders.customerNumber=customerCity.customerNumber AND `status`='Shipped'
group by city
order by totalSales;
SHOW PROFILE;