SQL to calculate difference from 1st day of Month to Date specified
Question
I'm working on a sql query to get differences. I have a table containing a reading, timestamp of the reading, id. My end goal is to get three differences. 1. Difference between a day prior to next day reading, 2. Difference between reading 7 day prior to the timestamp value, 3. Difference between reading starting from the 1st day of the month to every date specified.
I cracked down the 1st two items. Now i'm trying to crack the 3rd one. I know that it'll be easy to use functions, can anyone help me with the 3rd request.
expected result : reading on Nov 1 is 1000, on Nov 2 is 1020 and Nov 3 is 1050 , the difference on Nov 2 should be 20 and on Nov 3 should be 50.
If there is no data for day one of the month, take the most least data for the available date. Example, semptember has only from 24, so take the reading from sep 24.
Below is the example table.
+----+-----------+---------+----------------+----------------+-----------------+
| id | timestamp | Reading | 1DayDifference | 7DayDifference | monthDifference |
+----+-----------+---------+----------------+----------------+-----------------+
| A1 | 11/20/18 | 44182 | 0 | 300 | 541 |
| A1 | 11/19/18 | 44182 | 0 | 338 | 541 |
| A1 | 11/18/18 | 44182 | 0 | 338 | 541 |
| A1 | 11/17/18 | 44182 | 38 | 338 | 541 |
| A1 | 11/16/18 | 44144 | 197 | 300 | 503 |
| A1 | 11/15/18 | 43947 | 26 | 103 | |
| A1 | 11/14/18 | 43921 | 39 | 158 | |
| A1 | 11/13/18 | 43882 | 38 | 158 | |
| A1 | 11/12/18 | 43844 | 0 | 120 | |
| A1 | 11/11/18 | 43844 | 0 | 120 | |
| A1 | 11/10/18 | 43844 | 0 | 160 | |
| A1 | 11/09/18 | 43844 | 0 | 203 | |
| A1 | 11/08/18 | 43844 | 81 | 241 | |
| A1 | 11/06/18 | 43763 | 39 | 198 | |
| A1 | 11/05/18 | 43724 | 0 | 198 | |
| A1 | 11/04/18 | 43724 | 0 | 198 | |
| A1 | 11/03/18 | 43724 | 40 | 198 | |
| A1 | 11/02/18 | 43684 | 43 | 199 | |
| A1 | 11/01/18 | 43641 | 38 | 194 | |
| A1 | 10/31/18 | 43603 | 38 | 275 | 237 |
| A1 | 10/30/18 | 43565 | 39 | 317 | |
| A1 | 10/29/18 | 43526 | 0 | 317 | |
| A1 | 10/28/18 | 43526 | 0 | 317 | |
| A1 | 10/27/18 | 43526 | 41 | 317 | |
| A1 | 10/26/18 | 43485 | 38 | 276 | |
| A1 | 10/25/18 | 43447 | 119 | 238 | |
| A1 | 10/24/18 | 43328 | 80 | 119 | |
+----+-----------+---------+----------------+----------------+-----------------+
The SQL that i used to 1st two types.
SELECT id,
timestamp,
Reading,
Reading - lead(Reading,1,0) OVER( partition BY [id] ORDER BY timestamp desc) [OneDayDifference],
Reading - lead(Reading,7,0) OVER( partition BY [id] ORDER BY timestamp desc) [SevDayDifference]
FROM [dbo].[test_example] s
ORDER BY id, timestamp desc
Below is the Script to generate the above data.
CREATE TABLE [dbo].[test_Example](
[id] [nvarchar](50) NOT NULL,
[timestamp] [datetime2](7) NOT NULL,
[reading] [int] NOT NULL,
[OneDayDifference] [int] NOT NULL,
[SevDayDifference] [int] NOT NULL
) ON [PRIMARY]
GO
INSERT [dbo].[test_Example] ([id], [timestamp], [reading], [OneDayDifference], [SevDayDifference]) VALUES (N'A1', CAST(N'2018-11-19T00:01:38.0000000' AS DateTime2), 44182, 0, 338)
GO
INSERT [dbo].[test_Example] ([id], [timestamp], [reading], [OneDayDifference], [SevDayDifference]) VALUES (N'A1', CAST(N'2018-11-18T00:01:44.0000000' AS DateTime2), 44182, 0, 338)
GO
INSERT [dbo].[test_Example] ([id], [timestamp], [reading], [OneDayDifference], [SevDayDifference]) VALUES (N'A1', CAST(N'2018-11-17T00:01:35.0000000' AS DateTime2), 44182, 38, 338)
GO
INSERT [dbo].[test_Example] ([id], [timestamp], [reading], [OneDayDifference], [SevDayDifference]) VALUES (N'A1', CAST(N'2018-11-16T00:01:39.0000000' AS DateTime2), 44144, 197, 300)
GO
INSERT [dbo].[test_Example] ([id], [timestamp], [reading], [OneDayDifference], [SevDayDifference]) VALUES (N'A1', CAST(N'2018-11-15T00:01:47.0000000' AS DateTime2), 43947, 26, 103)
GO
INSERT [dbo].[test_Example] ([id], [timestamp], [reading], [OneDayDifference], [SevDayDifference]) VALUES (N'A1', CAST(N'2018-11-14T00:01:40.0000000' AS DateTime2), 43921, 39, 158)
GO
INSERT [dbo].[test_Example] ([id], [timestamp], [reading], [OneDayDifference], [SevDayDifference]) VALUES (N'A1', CAST(N'2018-11-13T00:01:38.0000000' AS DateTime2), 43882, 38, 158)
GO
INSERT [dbo].[test_Example] ([id], [timestamp], [reading], [OneDayDifference], [SevDayDifference]) VALUES (N'A1', CAST(N'2018-11-12T00:02:39.0000000' AS DateTime2), 43844, 0, 120)
GO
INSERT [dbo].[test_Example] ([id], [timestamp], [reading], [OneDayDifference], [SevDayDifference]) VALUES (N'A1', CAST(N'2018-11-11T00:01:37.0000000' AS DateTime2), 43844, 0, 120)
GO
INSERT [dbo].[test_Example] ([id], [timestamp], [reading], [OneDayDifference], [SevDayDifference]) VALUES (N'A1', CAST(N'2018-11-10T00:01:37.0000000' AS DateTime2), 43844, 0, 160)
GO
INSERT [dbo].[test_Example] ([id], [timestamp], [reading], [OneDayDifference], [SevDayDifference]) VALUES (N'A1', CAST(N'2018-11-09T00:01:37.0000000' AS DateTime2), 43844, 0, 203)
GO
INSERT [dbo].[test_Example] ([id], [timestamp], [reading], [OneDayDifference], [SevDayDifference]) VALUES (N'A1', CAST(N'2018-11-08T00:01:46.0000000' AS DateTime2), 43844, 81, 241)
GO
INSERT [dbo].[test_Example] ([id], [timestamp], [reading], [OneDayDifference], [SevDayDifference]) VALUES (N'A1', CAST(N'2018-11-06T00:01:36.0000000' AS DateTime2), 43763, 39, 198)
GO
INSERT [dbo].[test_Example] ([id], [timestamp], [reading], [OneDayDifference], [SevDayDifference]) VALUES (N'A1', CAST(N'2018-11-05T00:02:27.0000000' AS DateTime2), 43724, 0, 198)
GO
INSERT [dbo].[test_Example] ([id], [timestamp], [reading], [OneDayDifference], [SevDayDifference]) VALUES (N'A1', CAST(N'2018-11-04T00:01:37.0000000' AS DateTime2), 43724, 0, 198)
GO
INSERT [dbo].[test_Example] ([id], [timestamp], [reading], [OneDayDifference], [SevDayDifference]) VALUES (N'A1', CAST(N'2018-11-03T00:01:48.0000000' AS DateTime2), 43724, 40, 198)
GO
INSERT [dbo].[test_Example] ([id], [timestamp], [reading], [OneDayDifference], [SevDayDifference]) VALUES (N'A1', CAST(N'2018-11-02T00:01:33.0000000' AS DateTime2), 43684, 43, 199)
GO
INSERT [dbo].[test_Example] ([id], [timestamp], [reading], [OneDayDifference], [SevDayDifference]) VALUES (N'A1', CAST(N'2018-11-01T00:01:41.0000000' AS DateTime2), 43641, 38, 194)
GO
INSERT [dbo].[test_Example] ([id], [timestamp], [reading], [OneDayDifference], [SevDayDifference]) VALUES (N'A1', CAST(N'2018-10-31T00:01:32.0000000' AS DateTime2), 43603, 38, 275)
GO
INSERT [dbo].[test_Example] ([id], [timestamp], [reading], [OneDayDifference], [SevDayDifference]) VALUES (N'A1', CAST(N'2018-10-30T00:01:34.0000000' AS DateTime2), 43565, 39, 43565)
GO
INSERT [dbo].[test_Example] ([id], [timestamp], [reading], [OneDayDifference], [SevDayDifference]) VALUES (N'A1', CAST(N'2018-10-29T00:02:45.0000000' AS DateTime2), 43526, 0, 43526)
GO
INSERT [dbo].[test_Example] ([id], [timestamp], [reading], [OneDayDifference], [SevDayDifference]) VALUES (N'A1', CAST(N'2018-10-28T00:01:43.0000000' AS DateTime2), 43526, 0, 43526)
GO
INSERT [dbo].[test_Example] ([id], [timestamp], [reading], [OneDayDifference], [SevDayDifference]) VALUES (N'A1', CAST(N'2018-10-27T00:01:31.0000000' AS DateTime2), 43526, 41, 43526)
GO
INSERT [dbo].[test_Example] ([id], [timestamp], [reading], [OneDayDifference], [SevDayDifference]) VALUES (N'A1', CAST(N'2018-10-26T00:01:30.0000000' AS DateTime2), 43485, 38, 43485)
GO
INSERT [dbo].[test_Example] ([id], [timestamp], [reading], [OneDayDifference], [SevDayDifference]) VALUES (N'A1', CAST(N'2018-10-25T00:01:35.0000000' AS DateTime2), 43447, 119, 43447)
GO
INSERT [dbo].[test_Example] ([id], [timestamp], [reading], [OneDayDifference], [SevDayDifference]) VALUES (N'A1', CAST(N'2018-10-24T00:01:43.0000000' AS DateTime2), 43328, 43328, 43328)
GO
2 answers
solution1
1 ACCPTED 2018-11-21 01:12:28
Finding the first of the month requires looking backward a variable number of rows, so instead of LEAD() or LAG() you may use a correlated subquery within an apply . Note because you are "looking backward" I prefer using LAG() instead of reversing the order of timestamp and LEAD() , however either produces the same result.
nb: This subquery will find the earliest timestamp in any month, if that isn't desired then add and t.timestamp < dateadd(dd,1,dateadd(mm,datediff(mm,0,s.timestamp),0)) into the where clause
SELECT
id
, timestamp
, Reading
, Reading - LAG( Reading, 1, 0 ) OVER (PARTITION BY [id] ORDER BY timestamp) [OneDayDifference]
, Reading - LAG( Reading, 7, 0 ) OVER (PARTITION BY [id] ORDER BY timestamp) [SevDayDifference]
, reading - oa.prev_reading [ThisMonthDiff]
FROM [dbo].[test_example] s
outer apply (
select top(1) t.reading prev_reading
from [dbo].[test_example] t
where s.id = t.id
and t.timestamp >= dateadd(mm,datediff(mm,0,s.timestamp),0)
-- and t.timestamp < dateadd(dd,1,dateadd(mm,datediff(mm,0,s.timestamp),0))
order by t.timestamp
) oa
ORDER BY
id
, timestamp DESC
;
Result:
+----+----+------------+---------+------------------+------------------+---------------+
| | id | timestamp | Reading | OneDayDifference | SevDayDifference | ThisMonthDiff |
+----+----+------------+---------+------------------+------------------+---------------+
| 1 | A1 | 2018-11-19 | 44182 | 0 | 338 | 541 |
| 2 | A1 | 2018-11-18 | 44182 | 0 | 338 | 541 |
| 3 | A1 | 2018-11-17 | 44182 | 38 | 338 | 541 |
| 4 | A1 | 2018-11-16 | 44144 | 197 | 300 | 503 |
| 5 | A1 | 2018-11-15 | 43947 | 26 | 103 | 306 |
| 6 | A1 | 2018-11-14 | 43921 | 39 | 158 | 280 |
| 7 | A1 | 2018-11-13 | 43882 | 38 | 158 | 241 |
| 8 | A1 | 2018-11-12 | 43844 | 0 | 120 | 203 |
| 9 | A1 | 2018-11-11 | 43844 | 0 | 120 | 203 |
| 10 | A1 | 2018-11-10 | 43844 | 0 | 160 | 203 |
| 11 | A1 | 2018-11-09 | 43844 | 0 | 203 | 203 |
| 12 | A1 | 2018-11-08 | 43844 | 81 | 241 | 203 |
| 13 | A1 | 2018-11-06 | 43763 | 39 | 198 | 122 |
| 14 | A1 | 2018-11-05 | 43724 | 0 | 198 | 83 |
| 15 | A1 | 2018-11-04 | 43724 | 0 | 198 | 83 |
| 16 | A1 | 2018-11-03 | 43724 | 40 | 198 | 83 |
| 17 | A1 | 2018-11-02 | 43684 | 43 | 199 | 43 |
| 18 | A1 | 2018-11-01 | 43641 | 38 | 194 | 0 |
| 19 | A1 | 2018-10-31 | 43603 | 38 | 275 | 275 |
| 20 | A1 | 2018-10-30 | 43565 | 39 | 43565 | 237 |
| 21 | A1 | 2018-10-29 | 43526 | 0 | 43526 | 198 |
| 22 | A1 | 2018-10-28 | 43526 | 0 | 43526 | 198 |
| 23 | A1 | 2018-10-27 | 43526 | 41 | 43526 | 198 |
| 24 | A1 | 2018-10-26 | 43485 | 38 | 43485 | 157 |
| 25 | A1 | 2018-10-25 | 43447 | 119 | 43447 | 119 |
| 26 | A1 | 2018-10-24 | 43328 | 43328 | 43328 | 0 |
+----+----+------------+---------+------------------+------------------+---------------+
Above I have used outer apply which acts like an outer join (if no matching result is found the source row is still returned). If that isn't unnecessary then use cross apply instead.
Edit
SELECT
id
, format(timestamp, 'yyyy-MM-dd') [timestamp]
, Reading
, COALESCE(Reading - LAG( Reading, 1) OVER (PARTITION BY [id] ORDER BY timestamp),0) [OneDayDifference]
, COALESCE(Reading - LAG( Reading, 7) OVER (PARTITION BY [id] ORDER BY timestamp),0) [SevDayDifference]
, reading - ca.tr [ThisMonthDiff]
FROM [dbo].[test_example] s
cross apply (
select top(1) t.reading tr
from [dbo].[test_example] t
where s.id = t.id
and t.timestamp >= dateadd(mm,datediff(mm,0,s.timestamp),0)
order by t.timestamp
) ca
ORDER BY
id
, timestamp DESC
;
+----+----+------------+---------+------------------+------------------+---------------+
| | id | timestamp | Reading | OneDayDifference | SevDayDifference | ThisMonthDiff |
+----+----+------------+---------+------------------+------------------+---------------+
| 1 | A1 | 2018-11-19 | 44182 | 0 | 338 | 541 |
| 2 | A1 | 2018-11-18 | 44182 | 0 | 338 | 541 |
| 3 | A1 | 2018-11-17 | 44182 | 38 | 338 | 541 |
| 18 | A1 | 2018-11-01 | 43641 | 38 | 194 | 0 |
| 19 | A1 | 2018-10-31 | 43603 | 38 | 275 | 275 |
| 20 | A1 | 2018-10-30 | 43565 | 39 | 0 | 237 |
| 21 | A1 | 2018-10-29 | 43526 | 0 | 0 | 198 |
| 22 | A1 | 2018-10-28 | 43526 | 0 | 0 | 198 |
| 23 | A1 | 2018-10-27 | 43526 | 41 | 0 | 198 |
| 24 | A1 | 2018-10-26 | 43485 | 38 | 0 | 157 |
| 25 | A1 | 2018-10-25 | 43447 | 119 | 0 | 119 |
| 26 | A1 | 2018-10-24 | 43328 | 0 | 0 | 0 |
+----+----+------------+---------+------------------+------------------+---------------+
solution2
0 2018-11-20 19:37:37
不使用Lead() ，而是使用子查询获取相同Id ， year和month的前1行，按timestamp ASC排序，并计算与子查询返回的该行reading的差异。
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