OR (Transact-SQL)

boolean_expression

Is any valid expression that returns TRUE, FALSE, or UNKNOWN.

Boolean

OR returns TRUE when either of the conditions is TRUE.

The following table shows the result of the OR operator.

The following example uses the vEmployeeDepartmentHistory view to retrieve the names of Quality Assurance personnel who work either the evening shift or the night shift. If the parentheses are omitted, the query returns Quality Assurance employees who work the evening shift and all employees who work the night shift.

USE AdventureWorks2012;
GO
SELECT FirstName, LastName, Shift 
FROM HumanResources.vEmployeeDepartmentHistory
WHERE Department = 'Quality Assurance'
   AND (Shift = 'Evening' OR Shift = 'Night');

Here is the result set.

FirstName LastName Shift

------------ ---------------- -------

Andreas Berglund Evening

Sootha Charncherngkha Night

Reference