-- Getting Fancier (Inner Joins Still)

SELECT first_name, last_name, order_date, amount 
FROM customers
JOIN orders
    ON customers.id = orders.customer_id
ORDER BY order_date;

SELECT 
    first_name, 
    last_name, 
    SUM(amount) AS total_spent
FROM customers
JOIN orders
    ON customers.id = orders.customer_id
GROUP BY orders.customer_id
ORDER BY total_spent DESC;

Note: please see here for an animated visual of how left/right joins work.

-- LEFT JOINS

SELECT * FROM customers
LEFT JOIN orders
    ON customers.id = orders.customer_id;

SELECT first_name, last_name, order_date, amount
FROM customers
LEFT JOIN orders
    ON customers.id = orders.customer_id; 

SELECT 
    first_name, 
    last_name,
    IFNULL(SUM(amount), 0) AS total_spent
FROM customers
LEFT JOIN orders
    ON customers.id = orders.customer_id
GROUP BY customers.id
ORDER BY total_spent;