SQL Filtering
Filtering in SQL means narrowing down a result set to only the rows that meet specific conditions, using the WHERE clause - one of the most commonly used parts of a SELECT query.
Basic Syntax
SELECT * FROM customers
WHERE city = 'Noida';
Comparison Operators
- = - equal to
- != or <> - not equal to
- >, < - greater than, less than
- >=, <= - greater than or equal to, less than or equal to
Filtering Examples
-- Customers who joined after a certain date
SELECT * FROM customers WHERE signup_date > '2025-01-01';
-- Orders above a certain amount
SELECT * FROM orders WHERE amount >= 5000;
Filtering happens before sorting and grouping in a query's logical order - the database evaluates WHERE first to reduce the number of rows it has to work with.