Question

我想将每日温度数据汇总到每周数据中。目前它使用三个SELECT语句。有没有办法将它们组合成一个？

CREATE TABLE dailyX (
    city    INTEGER,    -- Index of city
    day          DATE,                          -- Date in yyyymmdd format
    first        FLOAT,                         -- first temperature reading for the day
    high         BINARY_DOUBLE,                 -- High temperature
    low          BINARY_DOUBLE,                 -- Low temperature
    last        FLOAT,                          -- Last temperature reading for the day
    count   INTEGER                             -- Number of readings
);

此stmt通过查找本周的最高和最低温度，然后将读数总和相加，将每日数据汇总到每周时间范围内。

SELECT city,to_char(day,'iw'), max(high), min(low), sum(NVL(count,0))
           FROM dailyX
          WHERE day > to_date(20140101,'YYYYMMDD')
       GROUP BY city,to_char(day,'iw');

这个stmt发现本周的第一个读数通常是周一的第一个读数。

select p_city,p_week,p_first
           FROM (select city p_city, to_char(day,'iw') p_week,first p_first,
                        rank() over (partition by city,to_char(day,'iw') order by day ASC) as RNK from dailyX
                  where day > to_date(20140101,'YYYYMMDD'))
          where RNK=1;

这个stmt找到本周的最后一次读数，这通常是星期五的最后一次读数。

select p_city,p_week,p_last
           FROM (select city p_city, to_char(day,'iw') p_week,last p_last,
                        rank() over (partition by city,to_char(day,'iw') order by day DESC) as RNK from dailyX
                  where day > to_date(20140101,'YYYYMMDD'))
          where RNK=1;

Answer 1

您可以使用keep：

SELECT city, to_char(day,'iw'), max(high), min(low), sum(NVL(count,0)),
       max(first) keep (dense_rank first order by day) as first,
       max(last) keep (dense_rank last order by day) as last
FROM dailyX
WHERE day > to_date(20140101,'YYYYMMDD')
GROUP BY city, to_char(day,'iw');

如何将每日温度数据汇总成每周数据？

1 个答案: