Instruction
Excellent! Of course, COUNT(*) isn't the only option. In fact, GROUP BY can be used together with many other functions. Take a look:
SELECT CustomerId, MAX(TotalSum) AS MaxCustomerSum FROM Order GROUP BY CustomerId;
We've replaced COUNT(*) with MAX(TotalSum). Can you guess what happens now?
That's right, instead of counting all the orders for specific clients, we'll find the order with the greatest value for each customer.
Exercise
Show all departments together with their lowest and highest salaries in 2014. Name the last two columns MinDepartmentSalary and MaxDepartmentSalary, respectively.
Stuck? Here's a hint!
Type:
SELECT Department, MIN(Salary) AS MinDepartmentSalary, MAX(Salary) AS MaxDepartmentSalary FROM Employee WHERE Year = 2014 GROUP BY Department;



