MySQL — Group By

Basic GROUP BY

SELECT category, COUNT(*) as count
FROM products
GROUP BY category;

GROUP BY with Aggregate Functions

SELECT category,
       COUNT(*) as count,
       AVG(price) as avg_price,
       MIN(price) as min_price,
       MAX(price) as max_price
FROM products
GROUP BY category;

GROUP BY Multiple Columns

SELECT category, brand, COUNT(*) as count
FROM products
GROUP BY category, brand;

GROUP BY Examples

-- Users per country
SELECT country, COUNT(*) as user_count
FROM users
GROUP BY country;

-- Average age by gender
SELECT gender, AVG(age) as avg_age
FROM users
GROUP BY gender;

-- Total sales by month
SELECT
    MONTH(order_date) as month,
    SUM(total) as total_sales
FROM orders
GROUP BY MONTH(order_date);

-- Products per category with total stock
SELECT
    category,
    COUNT(*) as product_count,
    SUM(stock) as total_stock
FROM products
GROUP BY category;

Mini Practice

Write MySQL code that:

1. Groups by single column
2. Uses aggregate functions
3. Groups by multiple columns
4. Groups with date functions

Up Next

Next: Learn about Having clause.