PostgreSQL – NOT Operator

The NOT operator is used to negate a condition or expression. The NOT operator can be used with various other operators and functions to create negative conditions. The syntax for using the NOT operator is quite straightforward:

NOT condition

Here are a couple of examples to illustrate its usage:

Using the NOT operator with a simple comparison:

Suppose you have a table named employees with columns employee_id and is_active, and you want to retrieve all records where the employees are not active. You would use the following SQL query:

SELECT * FROM employees WHERE NOT is_active; 

This query would fetch all rows from the employees table where the is_active column has a value of false.

Using the NOT operator with other conditions:

SELECT * FROM products WHERE NOT (price > 100); 

This query would retrieve all rows from the products table where the price is not greater than 100.

Remember that the NOT operator can be used in combination with various logical operators (AND, OR) and comparison operators (=, >, <, >=, <=, etc.) to create complex conditions that check for negations or the absence of certain conditions.