题解 | #牛客的课程订单分析(六)#

SELECT o.id, o.is_group_buy, 
        CASE WHEN o.client_id = 0
             THEN c.name = NULL
             ELSE c.name END AS client_name
FROM order_info o
LEFT JOIN CLIENT c
ON  o.client_id = c.id 
WHERE o.date >= '2025-10-15'
AND o.status = 'completed'
AND o.product_name IN ('C++', 'Java', 'Python')
AND o.user_id IN (SELECT user_id
                  FROM (SELECT user_id, COUNT(*) cnt
                        FROM order_info
                        WHERE STATUS = 'completed'
                        AND DATE >= '2025-10-15'
                        AND product_name IN ('C++', 'Java', 'Python')
                        GROUP BY user_id) AS user_id_cnt
                  WHERE cnt >= 2)
;