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SQL Server FAQ - What Are Logical/Boolean Operations

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(Continued from previous topic...)

What Are Logical/Boolean Operations?

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.

1. What Is a Boolean Value?
2. What Are Conditional Expressions?
3. What Are Comparison Operations?
4. How To Perform Comparison on Exact Numbers?
5. How To Perform Comparison on Floating Point Numbers?
6. How To Perform Comparison on Date and Time Values?
7. How To Perform Comparison on Character Strings?
8. What To Test Value Ranges with the BETWEEN Operator?
9. What To Test Value Lists with the IN Operator?
10. What To Perform Pattern Match with the LIKE Operator?
11. How To Use Wildcard Characters in LIKE Operations?
12. How To Test Subquery Results with the EXISTS Operator?
13. How To Test Values Returned by a Subquery with the IN Operator?
14. What Are Logical/Boolean Operations?