SQL AND, OR and NOT Operators

A single condition is rarely enough. “Furniture and under 5,000″, “Pune or Delhi”, “not cancelled”: AND, OR and NOT combine conditions in a WHERE clause. The one rule that catches everyone is precedence: AND binds tighter than OR, so you need parentheses more often than you think.

Sample data

AND: every condition must be true

Furniture that costs less than 5,000:

SELECT product_name, category, priceFROM productsWHERE category = 'Furniture'  AND price < 5000;

OR: at least one condition must be true

Employees based in Pune or Delhi:

SELECT first_name, cityFROM employeesWHERE city = 'Pune'   OR city = 'Delhi';

NOT: reverse a condition

All orders except the delivered ones:

SELECT order_id, statusFROM ordersWHERE NOT status = 'Delivered';

NOT also combines with other operators: NOT IN, NOT BETWEEN, NOT LIKE, IS NOT NULL.

Precedence: AND before OR

Goal: Electronics or Stationery products that are in stock. This first attempt looks right but is wrong:

SELECT product_name, category, stockFROM productsWHERE category = 'Electronics'   OR category = 'Stationery'  AND stock > 0;

Parentheses say what you mean:

SELECT product_name, category, stockFROM productsWHERE (category = 'Electronics' OR category = 'Stationery')  AND stock > 0;

AND, OR and NULL

SQL uses three-valued logic: a condition can be TRUE, FALSE or UNKNOWN (when NULL is involved). WHERE keeps only TRUE rows.

SELECT first_name, commissionFROM employeesWHERE commission > 5000 OR commission < 5000;

A realistic filter

Engineering or Sales employees hired before 2022 who earn at least 90,000:

SELECT first_name, dept_id, hire_date, salaryFROM employeesWHERE (dept_id = 1 OR dept_id = 2)  AND hire_date < '2022-01-01'  AND salary >= 90000ORDER BY salary DESC;

SELECT product_name, price, stockFROM productsWHERE price < 500 OR stock > 100;

SELECT order_id, order_date, statusFROM ordersWHERE status = 'Delivered'  AND order_date >= '2025-01-01'  AND order_date <= '2025-03-31';

AND / OR FAQ