PostgreSQL Aggregate Functions and Group By: Get the difference between the highest and lowest salaries

8. Write a query to get the difference between the highest and lowest salaries.

Sample Solution:

Code:

-- This SQL query calculates the salary difference between the highest and lowest salaries among employees.

SELECT MAX(salary) - MIN(salary) DIFFERENCE -- Calculates the difference between the maximum and minimum salaries from the employees table and labels the result column as "DIFFERENCE"
FROM employees; -- Specifies the table from which to retrieve data, in this case, the employees table

Explanation:

• The SQL query computes the salary difference between the highest and lowest salaries among employees.
• The SELECT statement is used to specify the calculation of the salary difference.
• MAX(salary) retrieves the highest salary from the salary column.
• MIN(salary) retrieves the lowest salary from the salary column.
• MAX(salary) - MIN(salary) calculates the difference between the highest and lowest salaries.
• The result column is labeled as "DIFFERENCE" using the alias DIFFERENCE.
• The FROM clause specifies the table from which to retrieve the data, which is the employees table in this case.

Sample table: employees

Output:

pg_exercises=# SELECT MAX(salary) - MIN(salary) DIFFERENCE
pg_exercises-# FROM employees;
 difference
------------
   21900.00
(1 row)

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