Aggregating and grouping 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..
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;
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';