Compare values for consecutive dates of same month - sql

I have a table
ID Value Date
1 10 2017-10-02 02:50:04.480
2 20 2017-10-01 07:28:53.593
3 30 2017-09-30 23:59:59.000
4 40 2017-09-30 23:59:59.000
5 50 2017-09-30 02:36:07.520
I compare Value with previous date. But, I don't need compare result between first day in current month and last day in previous month. For this table, I don't need to compare result between 2017-10-01 07:28:53.593 and 2017-09-30 23:59:59.000 How it can be done?
Result table for this example:
ID Value Date Diff
1 10 2017-10-02 02:50:04.480 10
2 20 2017-10-01 07:28:53.593 NULL
3 30 2017-09-30 23:59:59.000 10
4 40 2017-09-29 23:59:59.000 10
5 50 2017-09-28 02:36:07.520 NULL


You can use this.
SELECT * ,
LEAD(Value) OVER( PARTITION BY DATEPART(YEAR,[Date]), DATEPART(MONTH,[Date]) ORDER BY ID ) - Value AS Diff
FROM MyTable
ORDER BY ID


you can use a query like below
select *,
diff=LEAD(Value) OVER( PARTITION BY Month(Date),Year(Date) ORDER BY Date desc)-Value
from t
order by id asc
see working demo

Related

SQL Conditional update column value based on previous row value

I have a table with attendance dates in SQL Workbench/J. I need to define the attendance periods of the people, where any attendance period with gaps less or equal than 90 days are merged into a single attendance period and any gaps larger than that are considered a different attendance period. For example for a single person this is the table I have
id
year
start_date
end_date
prev_att_month
diff
1
2012
2012-08-01
2012-08-31
2012-07-01
31
1
2012
2012-07-01
2012-07-31
2012-04-01
91
1
2012
2012-04-01
2012-04-30
2012-03-01
31
1
2012
2012-03-01
2012-03-31
2012-02-01
29
1
2012
2012-02-01
2012-02-29
2012-01-01
31
1
2012
2012-01-01
2012-01-31
2011-12-01
31
1
2011
2011-12-01
2011-12-31
2011-11-01
30
1
2011
2011-11-01
2011-11-30
2011-10-01
31
1
2011
2011-10-01
2011-10-31
2011-09-01
30
1
2011
2011-09-01
2011-09-30
2011-08-01
31
1
2011
2011-08-01
2011-08-31
2011-07-01
31
1
2011
2011-07-01
2011-07-31
2011-05-01
61
1
2011
2011-05-01
2011-05-31
2011-04-01
30
1
2011
2011-04-01
2011-04-30
2011-03-01
31
1
2011
2011-03-01
2011-03-31
2011-02-01
28
1
2011
2011-02-01
2011-02-28
2010-08-01
184
1
2010
2010-08-01
2010-08-31
2010-07-01
31
1
2010
2010-07-01
2010-07-31
2010-06-01
30
1
2010
2010-06-01
2010-06-30
2010-05-01
31
1
2010
2010-05-01
2010-05-31
2010-04-01
30
1
2010
2010-04-01
2010-04-30
where I defined the previous attendance month column with a lag function and then found the difference between that column and the the start_date in the diff column. This way I can check the gaps between the attendance months
I want this output of the attendance periods with the 90 day rule explained above:
id
start_date
end_date
1
1/04/2010
31/08/2010
1
1/02/2011
30/04/2012
1
1/07/2012
31/08/2012
Does any one have an idea of how to do this?
So far I was just able to define the difference between the attendance months but since this is a large data set I have not been able to find a solution to define the attendance periods without making a row to row analysis.
with [table] as (
select id, year, start_date, end_date,
lag(start_date) over (partition by id order by id, year, start_date) as prev_att_month,
start_date-prev_att_month as diff
from source
)
select *
from [table]
where id = 1

One method would be to use a windowed COUNT to count how many times a value greater than 90 has appeared in the diff column, which provides a unique group number. Then you can just group your data into those groups and get the MIN and MAX values:
WITH Grps AS(
SELECT V.id,
V.year,
V.start_date,
V.end_date,
V.prev_att_month,
V.diff,
COUNT(CASE WHEN diff > 90 THEN 1 END) OVER (PARTITION BY ID ORDER BY V.start_date ASC) AS Grp
FROM (VALUES(1,2012,CONVERT(date,'20120801'),CONVERT(date,'20120831'),CONVERT(date,'2012-07-01'),31),
(1,2012,CONVERT(date,'20120701'),CONVERT(date,'20120731'),CONVERT(date,'2012-04-01'),91),
(1,2012,CONVERT(date,'20120401'),CONVERT(date,'20120430'),CONVERT(date,'2012-03-01'),31),
(1,2012,CONVERT(date,'20120301'),CONVERT(date,'20120331'),CONVERT(date,'2012-02-01'),29),
(1,2012,CONVERT(date,'20120201'),CONVERT(date,'20120229'),CONVERT(date,'2012-01-01'),31),
(1,2012,CONVERT(date,'20120101'),CONVERT(date,'20120131'),CONVERT(date,'2011-12-01'),31),
(1,2011,CONVERT(date,'20111201'),CONVERT(date,'20111231'),CONVERT(date,'2011-11-01'),30),
(1,2011,CONVERT(date,'20111101'),CONVERT(date,'20111130'),CONVERT(date,'2011-10-01'),31),
(1,2011,CONVERT(date,'20111001'),CONVERT(date,'20111031'),CONVERT(date,'2011-09-01'),30),
(1,2011,CONVERT(date,'20110901'),CONVERT(date,'20110930'),CONVERT(date,'2011-08-01'),31),
(1,2011,CONVERT(date,'20110801'),CONVERT(date,'20110831'),CONVERT(date,'2011-07-01'),31),
(1,2011,CONVERT(date,'20110701'),CONVERT(date,'20110731'),CONVERT(date,'2011-05-01'),61),
(1,2011,CONVERT(date,'20110501'),CONVERT(date,'20110531'),CONVERT(date,'2011-04-01'),30),
(1,2011,CONVERT(date,'20110401'),CONVERT(date,'20110430'),CONVERT(date,'2011-03-01'),31),
(1,2011,CONVERT(date,'20110301'),CONVERT(date,'20110331'),CONVERT(date,'2011-02-01'),28),
(1,2011,CONVERT(date,'20110201'),CONVERT(date,'20110228'),CONVERT(date,'2010-08-01'),184),
(1,2010,CONVERT(date,'20100801'),CONVERT(date,'20100831'),CONVERT(date,'2010-07-01'),31),
(1,2010,CONVERT(date,'20100701'),CONVERT(date,'20100731'),CONVERT(date,'2010-06-01'),30),
(1,2010,CONVERT(date,'20100601'),CONVERT(date,'20100630'),CONVERT(date,'2010-05-01'),31),
(1,2010,CONVERT(date,'20100501'),CONVERT(date,'20100531'),CONVERT(date,'2010-04-01'),30),
(1,2010,CONVERT(date,'20100401'),CONVERT(date,'20100430'),NULL,NULL))V(id,year,start_date,end_date,prev_att_month,diff))
SELECT id,
MIN(Start_date) AS Start_date,
MAX(End_Date) AS End_Date
FROM Grps
GROUP BY Id,
Grp
ORDER BY id,
Start_date;

selecting a date n days ago excluding weekends

I have a table with daily dates starting from 31st December 1999 up to 31st December 2050, excluding weekends.
Say given a particular date, for this example lets use 2019-03-14. I want to pick the date that was 30 days previous (the number of days needs to be flexible as it won't always be 30), ignoring weekends which in this case would be 2019-02-01.
How to do this?
I wrote the query below & it indeed lists 30 days previous to the specified date.
select top 30 Date
from DateDimension
where IsWeekend = 0 and Date <= '2019-03-14'
order by Date desc
So I thought I could use the query below to get the correct answer of 2019-02-01
;with ds as
(
select top 30 Date
from DateDimension
where IsWeekend = 0 and Date <= '2019-03-14'
)
select min(Date) from ds
However this doesn't work. It returns me the first date in my table, 1999-12-31.
2019-03-14
2019-03-13
2019-03-12
2019-03-11
2019-03-08
2019-03-07
2019-03-06
2019-03-05
2019-03-04
2019-03-01
2019-02-28
2019-02-27
2019-02-26
2019-02-25
2019-02-22
2019-02-21
2019-02-20
2019-02-19
2019-02-18
2019-02-15
2019-02-14
2019-02-13
2019-02-12
2019-02-11
2019-02-08
2019-02-07
2019-02-06
2019-02-05
2019-02-04
2019-02-01

TOP is meaningless without an ORDER BY, so you could do something like
;with ds as
(
select top 30 Date
from DateDimension
where IsWeekend = 0 and Date <= '2019-03-14'
order by Date DESC
)
select min(Date) from ds;
even better would be to use the ANSI syntax instead of TOP:
select Date
from DateDimension
where IsWeekend = 0 and Date <= '2019-03-14'
order by Date DESC
OFFSET 30 ROWS FETCH NEXT 1 ROW ONLY;
DISCLAIMER - code not tested since you did not provide DDL and sample data
HTH

Select data where days between two dates are part of a given month

My data looks like below, and I need to show the ids where interval between date1 and date2 are part of a given month/year parameter.
Eg.: for July 2018 I need ids from 1 to 7.
date1 date2 id
---------- ---------- --------
2017-11-01 2018-08-28 1
2018-06-05 2018-07-05 2
2018-06-05 2019-05-07 3
2018-06-05 2018-08-08 4
2018-07-01 2018-07-31 5
2018-07-07 2018-07-15 6
2018-07-27 2018-08-05 7
2018-06-01 2018-06-07 8
2018-08-03 2018-09-01 9

solution is quite simple
SELECT
id
FROM
YOUR_TABLE
WHERE
date1<=YOUR_DATE_END_OF_MONTH AND date2>=YOUR_DATE_START_OF_MONTH
e.g. for July 2018
SELECT
id
FROM
YOUR_TABLE
WHERE
date1<='2018-07-31' AND date2>='2018-07-01'
or if you do not need to calculate first end day of the month (but this do not use any indexes if exists on date1 and date2)
SELECT
id
FROM
YOUR_TABLE
WHERE
EXTRACT(YEAR FROM date1)*12 + EXTRACT(MONTH FROM date1)<=2018*12 + 7
AND EXTRACT(YEAR FROM date2)*12 + EXTRACT(MONTH FROM date2)>=2018*12 + 7

Computation of period Start date

I have a table that hold the start date and the end date of a financial period.
CHARGE_PERIOD_ID START_DATE END_DATE
13 2013-03-31 00:00:00.000 2013-04-27 00:00:00.000
14 2013-04-28 00:00:00.000 2013-05-25 00:00:00.000
15 2013-05-26 00:00:00.000 2013-06-29 00:00:00.000
16 2013-06-30 00:00:00.000 2013-07-27 00:00:00.000
17 2013-07-28 00:00:00.000 2013-08-24 00:00:00.000
18 2013-08-25 00:00:00.000 2013-09-28 00:00:00.000
19 2013-09-29 00:00:00.000 2013-10-26 00:00:00.000
20 2013-10-27 00:00:00.000 2013-11-23 00:00:00.000
21 2013-11-24 00:00:00.000 2013-12-28 00:00:00.000
22 2013-12-29 00:00:00.000 2014-01-25 00:00:00.000
23 2014-01-26 00:00:00.000 2014-02-22 00:00:00.000
24 2014-02-23 00:00:00.000 2014-03-29 00:00:00.000
The user of a report wants the current financial year split into 12 periods and want to give to feed in 2 parameters into the report , a year and a period number which will go into my sql . So something like #year=2014 #period=1 will be recieved . I have to write some sql to go to this table and set a period start date of 31/03/2014 and a period end date of 27/04/2014.
So in pseudo code:
Look up period 1 for 2014 and return period start date of 31/03/2014 and period end date of 27/04/2014.
#PERIOD_START_DATE = select the the first period that starts in March for the given year . all financial period starts in March.
#PERIOD_END_DATE = select the corresponding END_DATE from the table .
The question is how to begin to code this or my design approach? Should I create a function that calcualtes this or should I do a CTE and add a column which will hold the period number in the way they want etc .
Thinking about it more I think I need a mapping table . So the real question is can I do this without a mapping table ?

DECLARE #Year INT
DECLARE #Period INT
SET #Year= 2013
SET #Period = 1
;WITH CTE AS
(
SELECT *, ROW_NUMBER() OVER (PARTITION BY
CASE WHEN MONTH([START_DATE])<3 THEN YEAR([START_DATE]) -1 ELSE YEAR([START_DATE]) END
ORDER BY
CASE WHEN MONTH([START_DATE])<3 THEN YEAR([START_DATE]) - 1 ELSE YEAR([START_DATE]) END
,CASE WHEN MONTH([START_DATE])<3 THEN MONTH([START_DATE]) + 12 ELSE MONTH([START_DATE]) END
) AS RN
FROM Periods
)
SELECT * FROM CTE
WHERE RN = #Period
AND CASE WHEN MONTH([START_DATE])<3 THEN YEAR([START_DATE]) -1 ELSE YEAR([START_DATE]) END = #Year
SQLFiddle DEMO

Multiple rows selected from a date ranged row

Table example:
TableName:DownTime
Columns:
EventID - int,
ReasonID - int,
StartTime - DateTime,
EndTime - DateTime
I would like to calculate the daily downtime of each event over the last 30 days. However, an event could be down for multiple days, so the start time would could start 31 days prior and could end next week. So I need to return a row of data for that event 30 times. The event could also be 10 minutes long, so I need a row of data showing that.
So far I only get one row representing the entire event that occurs over 30 days instead of 30 rows.
MS SQL Server 2005 database
Thank you for any help.

You may want to create a date dimension table - a table that is a collection of days. The absolute simplest example for your purposes would have one column, date, and you would have one row for every consecutive day. Youu could then join this table to your downtime table:
from dim_date t join downtime d on t.date between convert(varchar(10), d.start_date, 120) and convert(varchar(10), d.end_date, 120)
This way if you have down time, you will get a row for every day containing down time.

before you try my code, you need to do a one time setup of a Numbers table. this will create a table names Numbers with a column Number having rows with values from 1 to 10,000:
SELECT TOP 10000 IDENTITY(int,1,1) AS Number
INTO Numbers
FROM sys.objects s1
CROSS JOIN sys.objects s2
ALTER TABLE Numbers ADD CONSTRAINT PK_Numbers PRIMARY KEY CLUSTERED (Number)
This Numbers table is joined to your existing table to "create" the rows you need, try this:
DECLARE #DownTime table (
EventID int,
ReasonID int,
StartTime DateTime,
EndTime DateTime)
INSERT INTO #DownTime VALUES (1,1,'9/10/2009 9:00am','9/10/2009 10:00am')
INSERT INTO #DownTime VALUES (2,1,'9/10/2009 1:00am','9/15/2009 1:00am')
INSERT INTO #DownTime VALUES (3,1,'9/10/2009' ,'9/11/2009')
SELECT
d.EventID,d.ReasonID,d.StartTime,d.EndTime
, DATEADD(day,Number-1,d.StartTime) AS SequenceDate
FROM #DownTime d
INNER JOIN Numbers n ON n.Number<=DATEDIFF(day,d.StartTime,d.EndTime)+1
OUTPUT:
EventID ReasonID StartTime EndTime SequenceDate
------- -------- ----------------------- ----------------------- -----------------------
1 1 2009-09-10 09:00:00.000 2009-09-10 10:00:00.000 2009-09-10 09:00:00.000
2 1 2009-09-10 01:00:00.000 2009-09-15 01:00:00.000 2009-09-10 01:00:00.000
2 1 2009-09-10 01:00:00.000 2009-09-15 01:00:00.000 2009-09-11 01:00:00.000
2 1 2009-09-10 01:00:00.000 2009-09-15 01:00:00.000 2009-09-12 01:00:00.000
2 1 2009-09-10 01:00:00.000 2009-09-15 01:00:00.000 2009-09-13 01:00:00.000
2 1 2009-09-10 01:00:00.000 2009-09-15 01:00:00.000 2009-09-14 01:00:00.000
2 1 2009-09-10 01:00:00.000 2009-09-15 01:00:00.000 2009-09-15 01:00:00.000
3 1 2009-09-10 00:00:00.000 2009-09-11 00:00:00.000 2009-09-10 00:00:00.000
3 1 2009-09-10 00:00:00.000 2009-09-11 00:00:00.000 2009-09-11 00:00:00.000
(9 row(s) affected)