Your First SQL Queries

SQL (Structured Query Language) is how you read and write data in MySQL. The four basic operations (SELECT, INSERT, UPDATE, DELETE) cover the vast majority of day-to-day work.

Create a sample table and insert some rows to practise with:

CREATE TABLE products (
    id       INT AUTO_INCREMENT PRIMARY KEY,
    name     VARCHAR(100) NOT NULL,
    price    DECIMAL(8, 2) NOT NULL,
    in_stock TINYINT(1) DEFAULT 1
);

INSERT INTO products (name, price) VALUES
    ('Widget A', 9.99),
    ('Widget B', 14.50),
    ('Gadget X', 49.00);

Read data with SELECT. Use WHERE to filter rows and ORDER BY to sort:

SELECT * FROM products;
SELECT name, price FROM products WHERE price < 20 ORDER BY price DESC;
SELECT COUNT(*) AS total FROM products WHERE in_stock = 1;

Update and delete rows; always use WHERE to avoid changing every row:

UPDATE products SET price = 12.99 WHERE name = 'Widget A';
DELETE FROM products WHERE id = 3;