Not operator negates a boolean input. The use of NOT negates an expression.

Syntax of  NOT Operator :

[ NOT ] boolean_expression

boolean_expression is valid boolean expression in sql server.

Return type of Not operator is Boolean. Not reverses the value of any boolean expression.

Below table shows the truth table of NOT operator.

Examples of NOT Operator :

Example 1 : Using NOT operator in where clause

SELECT ProductName,UnitPrice

FROM   Products

WHERE  NOT ProductName LIKE 'a%'

Output

ProductName                                  UnitPrice

Chai                                                   18.00

Chang                                                19.00

Chef Anton's Cajun Seasoning        22.00

Chef Anton's Gumbo Mix                21.35

Grandma's Boysenberry Spread       25.00

Uncle Bob's Organic Dried Pears   30.00

Northwoods Cranberry Sauce          40.00

Above query returns product name not starting with character ‘a’, as expression is negated by NOT operator.