题解 | #小破站9月上中下旬的用户充值数量#

重点1：CASE WHEN句法的使用 重点2：group by 分组

SELECT 
    -- 根据旬统计分组
    seg_date, 
    COUNT(1) AS cnt
FROM
    (

        SELECT 
            *,

            -- 根据时间定义旬
            CASE
                WHEN 
                    begin_date BETWEEN '2021-9-1' AND '2021-9-10' 
                THEN 
                    '上旬'
                WHEN 
                    begin_date BETWEEN '2021-9-11' AND '2021-9-20' 
                THEN 
                    '中旬'
                WHEN 
                    begin_date BETWEEN '2021-9-21' AND '2021-9-30' 
                THEN 
                    '下旬'
            END AS seg_date
FROM 
    detail_list_tb
WHERE 
    begin_date BETWEEN '2021-9-1' AND '2021-9-30'
)t
GROUP BY seg_dat;