I have a hard time trying to figure out the way the tables Sales_order and Employees are connected.

The question is "How can I extract data on the manager with the highest value of sales for 1990 within his department if there is no common column between these tables?"

CodePudding user response：

join indirectly via customer to get manager_id

select top 1 manager_id,sum(total)
from   salesorders so
join   customers cus on cus.customer_id = so.customer_id
join   employee emp on emp.employee_id = cus.salesperson_id
where  so.order_date between '1999-01-01' and '1999-12-31'
group  by manager_id
order sum(total) desc