sql - 获取记录创建之间的平均时间

Question

所以我有这样的数据：

UserID  CreateDate
1       10/20/2013 4:05
1       10/20/2013 4:10
1       10/21/2013 5:10
2       10/20/2012 4:03

我需要按每个用户分组，以获得 CreateDates 之间的平均时间。我想要的结果是这样的：

UserID  AvgTime(minutes)
1       753.5
2       0

如何找到为用户分组返回的所有记录的 CreateDates 之间的差异？

编辑：

使用 SQL Server 2012

Answer 1

试试这个：

SELECT  A.UserID,
        AVG(CAST(DATEDIFF(MINUTE,B.CreateDate,A.CreateDate) AS FLOAT)) AvgTime
FROM #YourTable A
OUTER APPLY (SELECT TOP 1 *
             FROM #YourTable
             WHERE UserID = A.UserID
             AND CreateDate < A.CreateDate
             ORDER BY CreateDate DESC) B
GROUP BY A.UserID

Answer 2

这种方法也应该有效。

小提琴演示在这里：

;WITH CTE AS (
    Select userId, createDate, 
           row_number() over (partition by userid order by createdate) rn
    from Table1
)
select t1.userid, 
       isnull(avg(datediff(second, t1.createdate, t2.createdate)*1.0/60),0) AvgTime
from CTE t1 left join CTE t2 on t1.UserID = t2.UserID and t1.rn +1 = t2.rn
group by t1.UserID;

更新：感谢@Lemark 指出number of diff = recordCount - 1

Answer 3

由于您使用的是 2012，因此您可以使用 Lead() 来执行此操作

with cte as
(select

         userid,
       (datediff(second, createdate, 
                    lead(CreateDate) over (Partition by userid order by createdate)
                   )/60) datdiff


From table1
)
select 
  userid,
  avg(datdiff) 
from  cte
group by userid

演示

Answer 4

像这样的东西：

;WITH CTE AS
(
   SELECT
      ROW_NUMBER() OVER (PARTITION BY UserID ORDER BY CreateDate) RN,
      UserID,
      CreateDate
   FROM Tbl
)
SELECT
  T1.UserID,
  AVG(DATEDIFF(mi, ISNULL(T2.CreateDate, T1.CreateDate), T1.CreateDate)) AvgTime
FROM CTE T1
  LEFT JOIN CTE T2
    ON T1.UserID = T2.UserID
      AND T1.RN = T2.RN - 1
GROUP BY T1.UserID

Answer 5

使用 SQL 2012，您可以使用ROW_NUMBER函数和自联接来查找每个组中的“上一个”行：

WITH Base AS
(
SELECT 
    ROW_NUMBER() OVER (PARTITION BY UserID ORDER BY CreateDate) RowNum,
    UserId, 
    CreateDate
FROM Users
)
SELECT 
    B1.UserID, 
    ISNULL(
       AVG(
           DATEDIFF(mi,B2.CreateDate,B1.CreateDate) * 1.0
       )
    ,0) [Average]
FROM Base B1
LEFT JOIN Base B2
    ON B1.UserID = B2.UserID
    AND B1.RowNum = B2.RowNum + 1
GROUP BY B1.UserId

虽然我对 UserID 1 得到了不同的答案 - 我得到的平均值为 (5 + 1500) / 2 = 752。

Answer 6

这仅在 2012 年有效。您可以使用LEAD分析功能：

CREATE TABLE dates (
  id integer,
  created datetime not null
);

INSERT INTO dates (id, created)
SELECT 1 AS id, '10/20/2013 4:05' AS created
UNION ALL SELECT 1, '10/20/2013 4:10'
UNION ALL SELECT 1, '10/21/2013 5:10'
UNION ALL SELECT 2, '10/20/2012 4:03';

SELECT id, isnull(avg(diff), 0)
FROM (
  SELECT id,
    datediff(MINUTE,
             created,
             LEAD(created, 1, NULL) OVER(partition BY id ORDER BY created)
             ) AS diff
  FROM dates
) as diffs
GROUP BY id;

http://sqlfiddle.com/#!6/4ce89/22