题解 | 查询下订单用户访问次数？

SELECT
    a.user_id,
    COUNT(DISTINCT a.info_id) AS visit_nums     -- 我感觉这个去重才是陷阱
FROM visit_tb AS a
INNER JOIN order_tb AS b
    ON (a.user_id = b.user_id)      -- 一位客户如果一天内有2个订单，JOIN会产生笛卡尔积效应
    AND b.order_time >= '2022-09-02 00:00:00'
    AND b.order_time < '2022-09-03 00:00:00'
WHERE a.visit_time >= '2022-09-02 00:00:00'
    AND a.visit_time < '2022-09-03 00:00:00'
GROUP BY a.user_id
ORDER BY visit_nums DESC;