The SQL provides an operator that can be used to change the Boolean result of an operation from true to false or from false to true. This operator is called NOT and comes in two flavors. To use it, in most cases, you can precede the expression with NOT or <>.

Imagine you perform filtering by form on a table that includes a column that lists a value as PG-13:

To negate such a filter, you can precede the string with NOT:

The result would include all records that do not include the value that was set on the right side of NOT. Remember that you can also use <> instead of NOT. Here is an example: