SELECT
    order_id,
    CASE
    WHEN YEAR(order_date) = YEAR(NOW()) THEN ‘Active’
    WHEN YEAR(order_date) = YEAR(NOW()) - 1 THEN ‘Last Year’
    WHEN YEAR(order_date) < YEAR(NOW()) - 1 THEN ‘Archived’
    ELSE ‘Future’
    END AS category
    FROM orders

    练习：
    image.png
    SELECT
    CONCAT(first_name, “ “ , last_name) AS customer,
    points,
    CASE
    WHEN points > 3000 THEN ‘Gold’,
    WHEN points >= 2000 THEN ‘Silver’
    ELSE ‘Bronze’
    END AS category
    FROM customers