What is the purpose of “not” in SQL?

In SQL, NOT is a logical operator used to negate conditions, reversing the result of the condition. When NOT is used in conjunction with other logical operators (such as AND, OR), it can be used to build more complex conditional expressions. For example, NOT can be used to represent meanings such as “not equal to”, “not contain”, or “not is”. By using NOT, SQL queries can become more flexible and precise.