Lesson 3: Filtering Data with WHERE

25 min read Beginner Lesson 3 of 12 13.5k learners

What is the WHERE Clause?

The WHERE clause filters records based on specific conditions. Without it, SQL queries return all rows in a table.

SQL

SELECT * FROM customers
WHERE city = 'New York';

Comparison Operators

= → Equal
<> or != → Not equal
>, <, >=, <= → Greater/less than

SQL

SELECT first_name, age FROM customers
WHERE age >= 30;

Logical Operators

AND → Combines multiple conditions (both must be true)
OR → At least one condition must be true
NOT → Negates a condition

SQL

SELECT first_name, city FROM customers
WHERE city = 'New York' OR city = 'Los Angeles';

Special Operators

IN → Match against a list of values
BETWEEN → Match within a range
LIKE → Match using patterns
IS NULL → Find null values