Logical operators in SQL are used to combine multiple conditions in a query’s WHERE clause. The main logical operators are AND, OR, and NOT.

• AND returns rows only if all conditions are true.
• OR returns rows if any one condition is true.
• NOT reverses the result of a condition.

• The AND operator requires all conditions to be true for a record to be selected.
• The OR operator requires at least one condition to be true.

SELECT * FROM Employees
WHERE Department = 'IT' AND Salary > 50000;
→ Returns employees in the IT department with salaries above 50,000.

SELECT * FROM Employees
WHERE Department = 'IT' OR Department = 'HR';
→ Returns employees from either IT or HR departments.

The NOT operator inverts the condition result.

SELECT * FROM Employees
WHERE NOT Department = 'HR';

Returns all employees except those in the HR department.

Yes. Logical operators can be combined for complex conditions. Parentheses () are used to define precedence.

SELECT * FROM Employees
WHERE (Department = 'IT' OR Department = 'HR')
AND Salary > 40000;

Returns employees from IT or HR with salaries above 40,000.

SQL evaluates logical operators in the following order:

1. NOT
2. AND
3. OR

Parentheses can be used to override this default precedence.