計算Oracle中每個作業的最近5個實例或最近3個月的平均時間

Question

我有一個包含作業名稱start_date和end_date的表格，我所看到的是最後10個實例或每個作業的平均時間最近3個月。請建議。

Job Start_Date End_Date 
A 1/2/2017 4:47 1/2/2017 4:48 
B 5/8/2017 23:09 5/8/2017 23:10 
C 2/28/2017 4:56 2/28/2017 4:57 
D 2/27/2017 4:05 2/27/2017 4:05 
A 2/18/2017 4:38 2/18/2017 4:38 
B 2/15/2017 4:23 2/15/2017 4:24 
C 2/25/2017 5:23 2/25/2017 5:24 
D 2/22/2017 8:27 2/22/2017 8:28 
A 2/24/2017 4:33 2/24/2017 4:34 
B 2/23/2017 4:44 2/23/2017 4:44 
C 2/17/2017 5:11 2/17/2017 5:11 
D 2/14/2017 4:28 2/14/2017 4:28 
A 2/16/2017 4:35 2/16/2017 4:35 
B 2/13/2017 4:33 2/13/2017 4:33 
C 2/11/2017 4:43 2/11/2017 4:43 
D 2/10/2017 4:14 2/10/2017 4:14 
A 2/9/2017 5:06 2/9/2017 5:06 
B 1/20/2017 4:28 1/20/2017 4:29 
C 2/6/2017 4:12 2/6/2017 4:12 
D 2/4/2017 4:11 2/4/2017 4:12 

Answer 1

如果我理解正確的，這僅僅是一個聚集查詢與過濾：

select job, avg(end_date - start_date) 
from t 
where start_date > sysdate - interval '3' month 
group by job; 

Answer 2

我假定這兩個起始日期和結束日期VARCHAR2 columns.If不是你可以直接使用，而不列to_date函數。

-- last 10 instances 
    SELECT job, 
      Avg (To_date(end_date, 'MM/DD/YYYY HH24:MI:SS') - 
       To_date(start_date, 'MM/DD/YYYY HH24:MI:SS')) * 1440 diff_in_minutes 
    FROM (SELECT job, 
        start_date, 
        end_date, 
        Row_number() 
        over (
         PARTITION BY id 
         ORDER BY end_date DESC) rn 
      FROM yourtable) 
    WHERE rn <= 10 
    GROUP BY job; 

--Last 3 months  
    SELECT job, 
      Avg (To_date(end_date, 'MM/DD/YYYY HH24:MI:SS') - 
       To_date(start_date, 'MM/DD/YYYY HH24:MI:SS')) * 1440 diff_in_minutes 
    FROM yourtable 
    WHERE start_date > SYSDATE - interval '3' month 
GROUP BY job;