Logical (Boolean) operations are performed on Boolean values with logical operators like 'AND', 'OR', or 'NOT'. Logical operations return Boolean values. SQL Server 2005 supports the following logical operations:

* AND - Returns TRUE if both operands are TRUE.

* OR - Returns TRUE if one of the operands is TRUE.

* NOT - Returns TRUE if the only operand is FALSE.

Logical operations are commonly used to combine Boolean values resulted from comparison operations. The following tutorial exercise shows you a good example:

DECLARE @income MONEY;

DECLARE @marriage_status VARCHAR(10);

SET @income = 55000.00;

SET @marriage_status = 'Single';

SELECT CASE WHEN

(@marriage_status = 'Married' AND @income < 65000)

OR (@marriage_status = 'Single' AND @income < 35000)

THEN 'Qualified for the benefit.'

ELSE 'Not qualified for the benefit.'

END;

GO

Not qualified for the benefit.