How is the “not” keyword used in SQL?

In SQL, NOT is a logical operator used to reverse the result of a condition. It can be used with other conditions, such as NOT IN, NOT LIKE, and NOT BETWEEN, to represent not including a value, not matching a pattern, or not within a certain range.

Here is an example of using NOT:

SELECT * FROM employees WHERE department_id NOT IN (1, 2, 3);

The query above will select all employees whose department ID is not 1, 2, or 3.