SQL每日一题(20200513)

Posted 2021-02-19 田灬禾-不忘初心,方得始終

引自：https://mp.weixin.qq.com/s?__biz=MzA3MTg4NjY4Mw==&mid=2457305432&idx=4&sn=f945fef1267983d9aad405d2b1397c22&chksm=88a5936cbfd21a7a901ab9a764285477a36987a1a17193dd194025d4e11f962dcf0e5580377a&mpshare=1&scene=1&srcid=&sharer_sharetime=1589379613101&sharer_shareid=18c156b37f741bf9989098e28bf33e09&exportkey=Abczad4uJ2LGc0e82s%2FlStE%3D&pass_ticket=W3S3KdK%2BnUpk0DsaHX5cmRIsPCVEMCdRjXKBld%2Bn9Ffjas8N%2BjYwZWCDsVPti4EQ#rd

感谢出题者，如有冒犯，请与我联系，希望和大家一起学习交流。(目前使用oracle数据库环境编写sql)

 

 

题目

有一个商场，每日人流量信息被记录在这三列信息中：序号 (id)、日期 (date)、 人流量 (people)。请编写一个查询语句，找出高峰期时段，要求连续三天及以上，并且每天人流量均不少于100。例如，表 stadium：
 

 

 

    对于上面的示例数据，输出为：

 

 

该如何写这个SQL？

 

读者可以试着自己思考写下，再往下翻... 如有不同解题方式，大家一起交流。

 

 

 

 

 

ID这边当作是连续有序值，如果 实际环境中不是的，以下sql需要再嵌一层，列出有序列代替ID:

sys@WIL>     WITH T AS
  2       (SELECT 1 ID, DATE \'2019-01-01\' DT, 10 PEOPLE
  3          FROM DUAL
  4        UNION ALL
  5        SELECT 2 ID, DATE \'2019-01-02\' DT, 109 PEOPLE
  6          FROM DUAL
  7        UNION ALL
  8        SELECT 3 ID, DATE \'2019-01-03\' DT, 150 PEOPLE
  9          FROM DUAL
 10        UNION ALL
 11        SELECT 4 ID, DATE \'2019-01-04\' DT, 99 PEOPLE
 12          FROM DUAL
 13        UNION ALL
 14        SELECT 5 ID, DATE \'2019-01-05\' DT, 145 PEOPLE
 15          FROM DUAL
 16        UNION ALL
 17        SELECT 6 ID, DATE \'2019-01-06\' DT, 1455 PEOPLE
 18          FROM DUAL
 19        UNION ALL
 20        SELECT 7 ID, DATE \'2019-01-07\' DT, 199 PEOPLE
 21          FROM DUAL
 22        UNION ALL
 23        SELECT 8 ID, DATE \'2019-01-08\' DT, 188 PEOPLE
 24          FROM DUAL)
 25      SELECT ID, DT, PEOPLE
 26        FROM (SELECT TT.*, COUNT(*) OVER(PARTITION BY GID) CN
 27                FROM (SELECT T.*, ID - ROW_NUMBER() OVER(ORDER BY DT) GID
 28                        FROM T
 29                       WHERE PEOPLE > 100) TT)
 30       WHERE CN >= 3
 31       ORDER BY 2;

        ID DT             PEOPLE
---------- ---------- ----------
         5 2019-01-05        145
         6 2019-01-06       1455
         7 2019-01-07        199
         8 2019-01-08        188