Aggregate and group data

You use AVG, SUM, or MAX functions to aggregate data, and the GROUP BY clause to group data query results in one or more table columns..

1. Construct a query that returns the average salary of all employees in the engineering department grouped by year.

   SELECT year, AVG(salary)
   FROM Employees
   WHERE Department = 'engineering' GROUP BY year;

2. Construct an implicit grouping query to get the highest paid employee.

   SELECT MAX(salary) as highest_pay, 
   AVG(salary) as average_pay
   FROM Employees
   WHERE Department = 'engineering';