The OR operator is used in a WHERE clause to combine two or more conditions.

  • A row is included in the result if any of the conditions are true.
  • If all conditions are false, the row is excluded.

Basic syntax:

SELECT column1, column2, ...
FROM table_name
WHERE condition1 OR condition2 [OR condition3 ...];

Step 1: Example table

Assume the Employees table:

EmployeeID FirstName LastName Department Salary
1 John Doe IT 5000
2 Jane Smith HR 4500
3 Mike Brown IT 6000
4 Sara White HR 4700
5 Tom Green IT 5200

Step 2: Using OR to filter rows

Example: Employees in IT department OR salary greater than 5000

SELECT FirstName, Department, Salary
FROM Employees
WHERE Department = 'IT' OR Salary > 5000;

Result:

FirstName Department Salary
John IT 5000
Mike IT 6000
Tom IT 5200

Explanation:

  • John → IT → included
  • Mike → IT and Salary > 5000 → included
  • Tom → IT and Salary > 5000 → included
  • Jane and Sara → HR and Salary ≤ 5000 → excluded

Step 3: Using multiple OR conditions

Example: Employees in IT OR HR OR salary > 5000

SELECT FirstName, Department, Salary
FROM Employees
WHERE Department = 'IT' OR Department = 'HR' OR Salary > 5000;

Result:

FirstName Department Salary
John IT 5000
Jane HR 4500
Mike IT 6000
Sara HR 4700
Tom IT 5200

Here, all employees match at least one condition.

Step 4: Combining AND and OR

When combining AND and OR, use parentheses to clarify logic.

Example: IT department AND (salary > 5000 OR EmployeeID = 1)

SELECT FirstName, Department, Salary
FROM Employees
WHERE Department = 'IT' AND (Salary > 5000 OR EmployeeID = 1);

Result:

FirstName Department Salary
John IT 5000
Mike IT 6000
Tom IT 5200

Parentheses ensure correct order of evaluation.

Step 5: Using IN as a shortcut for OR

Instead of multiple ORs, you can use IN:

SELECT FirstName, Department
FROM Employees
WHERE Department IN ('IT', 'HR');

Equivalent to: WHERE Department = 'IT' OR Department = 'HR'

Categorized in:

SQL Server,