Logical OperatorsThe logical operators AND, NOT, and OR follow the tri-state logic shown in table below. The AND and OR are binary operators; NOT is a unary operator.
Table: Logic Truth Table
As the truth table shown below, the AND returns TRUE only if both its operands are true. On the other hand, the OR returns TRUE if either of its operands is true. The NOT returns the opposite value (logical negation) of its operand. For illustration, NOT TRUE returns FALSE.The NOT NULL returns NULL as nulls are indeterminate. It follows that if you apply the NOT operator to a null, the answer is also indeterminate.