题解 | #牛客的课程订单分析(二)#

sql分步计算

SELECT
a.user_id,
b.first_buy_date,
a.cnt
FROM
(
SELECT
user_id,COUNT(1) AS cnt
FROM
order_info 
WHERE
date > '2025-10-15'
AND
status='completed'
AND
product_name IN('C++','Java','Python')
GROUP BY
user_id
HAVING
COUNT(1) >= 2
)a,
(
SELECT
min(date) AS first_buy_date,
user_id
FROM
order_info
WHERE
date > '2025-10-15'
AND
status='completed'
AND
product_name IN('C++','Java','Python')
GROUP BY
user_id
)b
WHERE
a.user_id = b.user_id
ORDER BY
a.user_id