题解 | #牛客的课程订单分析(六)#

SELECT
    a.id,
    a.is_group_buy,
    IF (a.is_group_buy = 'Yes', NULL, c.name) as cn
FROM
    order_info a
    JOIN (
        SELECT
            user_id
        FROM
            order_info
        WHERE
            status = 'completed'
        GROUP BY
            user_id
        HAVING
            count(1) >= 2
    )  as uc ON a.user_id = uc.user_id
    LEFT JOIN client c ON a.client_id = c.id
WHERE
    a.status = 'completed'
    AND a.product_name in('C++','Java','Python')
ORDER BY a.id