题解 | SQLW17 统计商家不同会员每日访问人次及访问人数

WITH t1 AS (
    SELECT a.user_id,
           b.vip
    FROM visit_tb a
    LEFT JOIN uservip_tb b
    ON a.user_id = b.user_id
),
t2 AS (
    SELECT vip,
           count(user_id) AS visit_nums,
           count(DISTINCT user_id) AS visit_users
    FROM t1
    GROUP BY vip
    ORDER BY visit_nums DESC 
)SELECT * FROM t2;

# 这道题关键在于是否去重计数！