[英]how to aggregate data base per month and previous data with oracle sql
假設我們有一個簡單的表格“示例”,如下所示:
id time
1 2-2-20
2 3-1-20
3 15-2-20
4 20-3-20
我想按每個月計算包含上個月數據的行,並獲取每個月的平均數據(除以指定月份的行):
month rows_num avg_per_day
1-20 1 1/31
2-20 2+1 2/29
3-20 2+1+1 1/31
我正在考慮是否可以像這樣使用 sql 但不包含上個月的數據並且不知道如何處理平均值:
select count(*) from example group by trunc(to_date(trunc(time)),'MONTH')
任何人都可以幫助我嗎?
您可以使用:
select to_char(time, 'yyyy-mm') as month,
sum(count(*)) over (order by min(time)) as rows_num,
count(*) / extract(day from last_day(time))
from t
group by to_char(time, 'yyyy-mm'), extract(day from last_day(time))
order by min(time);
我對月份的格式略有不同,但您可以根據自己的喜好進行格式設置。
盡管查詢的 output 看起來相當簡單,但編寫內聯視圖以生成可在外部 SELECT 中使用的值可能是一個優勢,例如(使用您的示例表)
表格和數據
create table example ( id, day_ )
as
select 1, date '2020-02-02' from dual union all -- 2-2-20
select 2, date '2020-01-03' from dual union all -- 3-1-20
select 3, date '2020-02-15' from dual union all -- 15-2-20
select 4, date '2020-03-20' from dual -- 20-3-20
;
第一步(將其用於“內聯視圖”)
select
to_char( day_, 'MM-YY') month_
, to_char( extract ( day from last_day( day_ ) ) ) lastday_
, count(*) over ( order by to_char( day_, 'MM-YY') ) runningtotal_
, row_number() over ( partition by to_char( day_, 'MM-YY') order by day_ ) rn_
from example ;
-- result
+------+--------+-------------+---+
|MONTH_|LASTDAY_|RUNNINGTOTAL_|RN_|
+------+--------+-------------+---+
|01-20 |31 |1 |1 |
|02-20 |29 |3 |1 |
|02-20 |29 |3 |2 |
|03-20 |31 |4 |1 |
+------+--------+-------------+---+
最終查詢
select
month_
, runningtotal_ rows_num
, round( max( rn_ ) / lastday_, 5 ) avg_per_day
, to_char( max( rn_ ) ) || '/' || to_char( lastday_ ) avg_per_day
from (
select
to_char( day_, 'MM-YY') month_
, to_char( extract ( day from last_day( day_ ) ) ) lastday_
, count(*) over ( order by to_char( day_, 'MM-YY') ) runningtotal_
, row_number() over ( partition by to_char( day_, 'MM-YY') order by day_ ) rn_
from example
)
group by month_, runningtotal_, lastday_
order by month_
;
-- result
+------+--------+-----------+-----------+
|MONTH_|ROWS_NUM|AVG_PER_DAY|AVG_PER_DAY|
+------+--------+-----------+-----------+
|01-20 |1 |0.03226 |1/31 |
|02-20 |3 |0.06897 |2/29 |
|03-20 |4 |0.03226 |1/31 |
+------+--------+-----------+-----------+
DBfiddle 在這里。
注意:(對我來說)您需要哪種形式的“AVG_PER_DAY”還不是很清楚。 只需從外部 SELECT 中刪除您不需要的行。
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