The sum of a column with real values can be calculated using the SUM() aggregate function. For example, the query that provides the sum of all the scores of class X students can be given by –  SELECT SUM(score) FROM students WHERE class=‘X’; The average value of a column with real values can be calculated using the AVG() aggregate function. For example, the query that provides the average salary of the employees in an organization can be given by –  SELECT AVG(salary) FROM employees;