What Is SQL?

SQL (Structured Query Language) is the standard language for relational databases. Used to create, read, update, and delete data in MySQL, PostgreSQL, SQLite, and more.

Basic Queries

-- Select all users
SELECT * FROM users;

-- Select specific columns with condition
SELECT name, email FROM users WHERE age > 18;

-- Order results
SELECT * FROM products ORDER BY price DESC;

Inserting and Updating

-- Insert new row
INSERT INTO users (name, email, age)
VALUES ('John', 'john@email.com', 25);

-- Update existing row
UPDATE users SET age = 26 WHERE id = 1;

-- Delete row
DELETE FROM users WHERE id = 1;

Joining Tables

-- Get users with their orders
SELECT users.name, orders.total
FROM users
INNER JOIN orders ON users.id = orders.user_id
WHERE orders.status = 'completed';

Conclusion

SQL is essential for any backend developer. Master CRUD operations and JOINs first, then explore advanced features.