CASE

SELECT
    order_id,
    amount,

    CASE
        WHEN amount >= 2000
            THEN 'High'

        WHEN amount >= 1000
            THEN 'Medium'

        ELSE 'Low'

    END AS order_segment

FROM orders;

SELECT
    user_id,

    SUM(
        CASE
            WHEN status = 'completed'
            THEN 1
            ELSE 0
        END
    ) AS completed_orders,

    SUM(
        CASE
            WHEN status = 'cancelled'
            THEN 1
            ELSE 0
        END
    ) AS cancelled_orders

FROM orders

GROUP BY user_id;