If I had a large table (100000 + entries) which had service records or perhaps admission records. How would I find all the instances of re-occurrence within a set number of days.
The table setup could be something like this likely with more columns.
Record ID Customer ID Start Date Time Finish Date Time
1 123456 24/04/2010 16:49 25/04/2010 13:37
3 654321 02/05/2010 12:45 03/05/2010 18:48
4 764352 24/03/2010 21:36 29/03/2010 14:24
9 123456 28/04/2010 13:49 31/04/2010 09:45
10 836472 19/03/2010 19:05 20/03/2010 14:48
11 123456 05/05/2010 11:26 06/05/2010 16:23
What I am trying to do is work out a way to select the records where there is a re-occurrence of the field [Customer ID] within a certain time period (< X days). (Where the time period is Start Date Time of the 2nd occurrence - Finish Date Time of the first occurrence.
This is what I would like it to look like once it was run for say x=7
Record ID Customer ID Start Date Time Finish Date Time Re-occurence
9 123456 28/04/2010 13:49 31/04/2010 09:45 1
11 123456 05/05/2010 11:26 06/05/2010 16:23 2
I can solve this problem with a smaller set of records in Excel but have struggled to come up with a SQL solution in MS Access. I do have some SQL queries that I have tried but I am not sure I am on the right track.
Any advice would be appreciated.
I think this is a clear expression of what you want. It's not extremely high performance but I'm not sure that you can avoid either correlated sub-query or a cartesian JOIN of the table to itself to solve this problem. It is standard SQL and should work in most any engine, although the details of the date math may differ:
SELECT * FROM YourTable YT1 WHERE EXISTS
(SELECT * FROM YourTable YT2 WHERE
YT2.CustomerID = YT1.CustomerID AND YT2.StartTime <= YT2.FinishTime + 7)
In order to accomplish this you would need to make a self join as you are comparing the entire table to itself. Assuming similar names it would look something like this:
select r1.customer_id, min(start_time), max(end_time), count(1) as reoccurences
from records r1,
records r2
where r1.record_id > r2.record_id -- this ensures you don't double count the records
and r1.customer_id = r2.customer_id
and r1.finish_time - r2.start_time <= 7
group by r1.customer_id
You wouldn't be able to easily get both the record_id and the number of occurences, but you could go back and find it by correlating the start time to the record number with that customer_id and start_time.
This will do it:
declare #t table(Record_ID int, Customer_ID int, StartDateTime datetime, FinishDateTime datetime)
insert #t values(1 ,123456,'2010-04-24 16:49','2010-04-25 13:37')
insert #t values(3 ,654321,'2010-05-02 12:45','2010-05-03 18:48')
insert #t values(4 ,764352,'2010-03-24 21:36','2010-03-29 14:24')
insert #t values(9 ,123456,'2010-04-28 13:49','2010-04-30 09:45')
insert #t values(10,836472,'2010-03-19 19:05','2010-03-20 14:48')
insert #t values(11,123456,'2010-05-05 11:26','2010-05-06 16:23')
declare #days int
set #days = 7
;with a as (
select record_id, customer_id, startdatetime, finishdatetime,
rn = row_number() over (partition by customer_id order by startdatetime asc)
from #t),
b as (
select record_id, customer_id, startdatetime, finishdatetime, rn, 0 recurrence
from a
where rn = 1
union all
select a.record_id, a.customer_id, a.startdatetime, a.finishdatetime,
a.rn, case when a.startdatetime - #days < b.finishdatetime then recurrence + 1 else 0 end
from b join a
on b.rn = a.rn - 1 and b.customer_id = a.customer_id
)
select record_id, customer_id, startdatetime, recurrence from b
where recurrence > 0
Result:
https://data.stackexchange.com/stackoverflow/q/112808/
I just realize it should be done in access. I am so sorry, this was written for sql server 2005. I don't know how to rewrite it for access.
Related
I have some date data as follows:-
Person | Date
1 | 1/1/2000
1 | 6/1/2000
1 | 11/1/2000
1 | 21/1/2000
1 | 28/1/2000
I need to delete rows within 14 days of a previous one. However, if a row is deleted, it should not later become a 'base' date against which later rows are checked. It's perhaps easier to show the results needed:-
Person | Date
1 | 1/1/2000
1 | 21/1/2000
My feeling is that recursive SQL will be needed but I'm not sure how to set it up. I'll be running this on Teradata.
Thanks.
--- Edit ---
Well, this is embarrassing. It turns out this question has been asked before - and it was asked by me! See this old question for an excellent answer from #dnoeth:-
Drop rows identified within moving time window
Use recursive tables. Use ROWNUMBER() to Order and Number the dates.
DATEDIFF() to receive the number of days passed from previous date
Maybe SQL2012 and above can simplify using SUM() OVER PARTITION with a RANGE
I didn't find it useful in this case
DECLARE #Tab TABLE ([MyDate] SMALLDATETIME)
INSERT INTO #Tab ([MyDate])
VALUES
('2000-01-06'),
('2000-01-01'),
('2000-01-11'),
('2000-01-21'),
('2000-01-28')
;
WITH DOrder (MyDate, SortID) AS (
SELECT MyDate,
ROW_NUMBER() OVER (ORDER BY MyDate)SortID
FROM #Tab t)
,Summarize(MyDate, SortID, sSum, rSum ) AS (
SELECT MyDate, SortID, 0, 0 rSum
FROM DOrder WHERE SortID = 1
UNION ALL
SELECT t.MyDate, t.SortID, DATEDIFF(D, ISNULL(s.MyDate,t.MyDate), t.MyDate) rSum,
CASE WHEN DATEDIFF(D, ISNULL(s.MyDate,t.MyDate), t.MyDate) + s.rSum>14 THEN 0
ELSE DATEDIFF(D, ISNULL(s.MyDate,t.MyDate), t.MyDate)
END rSum
FROM DOrder t INNER JOIN Summarize s
ON (t.SortID = s.SortID+1))
SELECT MyDate
FROM Summarize
WHERE rSum=0
I have a table PostingPeriod that uses a company calendar to track all working days. Simplified, it looks like this:
Date Year Quarter Month Day IsWorkingDay
25.06.2015 2015 2 6 25 1
26.06.2015 2015 2 6 26 1
27.06.2015 2015 2 6 27 0
I have another table that contains all purchase lines with the Orderdate, confirmed delivery date from the vendor and the maximum allowed timeframe in working days between orderdate and deliverydate:
PurchID OrderDate ConfDelivery DeliveryDays
1234 14.04.2015 20.05.2015 30
1235 14.04.2015 24.05.2015 20
I want to create a new column that returns the maximum allowed Date (regardless of workday or not) for each order. The usual approach (Workingdays / 5 to get weeks, multiplied by 7 to get days) doesn't work, as all holidays etc need to be taken into consideration.
As this is for a DWH that will feed an OLAP database, performance is not an issue.
You could do this by assigning each working day an arbitrary index using ROW_NUMBER, e.g.
SELECT Date, WorkingDayIndex = ROW_NUMBER() OVER(ORDER BY Date)
FROM dbo.Calendar
Which will give you something like:
Date WorkingDayIndex
-----------------------------
2015-04-27 80
2015-04-28 81
2015-04-29 82
2015-04-30 83
2015-05-01 84
2015-05-05 85
2015-05-06 86
2015-05-07 87
Then if you want to know the date that is n working days from a given date, find the date with an index n higher, i.e. 2015-04-27 has an index of 80, therefore 5 working days later would have an index of 85 which yields 2015-05-05.
FULL WORKING EXAMPLE
/***************************************************************************************************************************/
-- CREATE TABLES AND POPULATE WITH TEST DATA
SET DATEFIRST 1;
DECLARE #Calendar TABLE (Date DATE, IsWorkingDay BIT);
INSERT #Calendar
SELECT TOP 365 DATEADD(DAY, ROW_NUMBER() OVER(ORDER BY object_id), '20141231'), 1 FROM sys.all_objects;
UPDATE #Calendar
SET IsWorkingDay = 0
WHERE DATEPART(WEEKDAY, Date) IN (6, 7)
OR Date IN ('2015-01-01', '2015-04-03', '2015-04-06', '2015-05-04', '2015-05-25', '2015-08-31', '2015-12-25', '2015-12-28');
DECLARE #T TABLE (PurchID INT, OrderDate DATE, ConfDeliveryDate DATE, DeliveryDays INT);
INSERT #T VALUES (1234, '20150414', '20150520', 30), (1235, '20150414', '20150524', 20);
/***************************************************************************************************************************/
-- ACTUAL QUERY
WITH WorkingDayCalendar AS
( SELECT *, WorkingDayIndex = ROW_NUMBER() OVER(ORDER BY Date)
FROM #Calendar
WHERE IsWorkingDay = 1
)
SELECT *
FROM #T AS t
INNER JOIN WorkingDayCalendar AS c1
ON c1.Date = t.OrderDate
INNER JOIN WorkingDayCalendar AS c2
ON c2.WorkingDayIndex = c1.WorkingDayIndex + t.DeliveryDays;
If this is a common requirement, then you could just make WorkingDayIndex a fixed field on your calendar table so you don't need to calculate it each time it is required.
Starting from OrderDate, the Date if you advance N(DeliveryDays) WorkingDays.
If i understood correctly you want something like this:
select
PurchID,
OrderDate,
ConfDelivery,
DeliveryDay,
myDays.[Date] myWorkingDayDeliveryDate
from Purchases p
outer apply (
select
[Date]
from (
select
ROW_NUMBER() OVER (
ORDER BY
Date
) myDays,
[Date]
from PostingPeriod pp
where
IsWorkingDay = 1 and
pp.date >= p.OrderDate
) myDays
where
myDays = p.DeliveryDay
) myDays
You'd have to do something like
SELECT OrderDate.PurchId, OrderDate.OrderDate, OrderDate.DeliveryDays, Aux.Counter, Aux.Date
FROM OrderDate, (SELECT row_number() OVER (ORDER BY Date) AS Counter, Date FROM PostingPeriod WHERE IsWorkingDay = 1 ) Aux
WHERE Counter = DeliveryDays
ORDER BY 1
Basically, you'd need all the dates inserted in the table PostingPeriod (weekends and holidays would have a IsWorkingDay = 0, rest of the days = 1)
and this would provide you the minimal date by summing the OrderDate with the ammount of working days
I have s table that lists absences(holidays) of all employees, and what we would like to find out is who is away today, and the date that they will return.
Unfortunately, absences aren't given IDs, so you can't just retrieve the max date from an absence ID if one of those dates is today.
However, absences are given an incrementing ID per day as they are inputt, so I need a query that will find the employeeID if there is an entry with today's date, then increment the AbsenceID column to find the max date on that absence.
Table Example (assuming today's date is 11/11/2014, UK format):
AbsenceID EmployeeID AbsenceDate
100 10 11/11/2014
101 10 12/11/2014
102 10 13/11/2014
103 10 14/11/2014
104 10 15/11/2014
107 21 11/11/2014
108 21 12/11/2014
120 05 11/11/2014
130 15 20/11/2014
140 10 01/03/2015
141 10 02/03/2015
142 10 03/03/2015
143 10 04/03/2015
So, from the above, we'd want the return dates to be:
EmployeeID ReturnDate
10 15/11/2014
21 12/11/2014
05 11/11/2014
Edit: note that the 140-143 range couldn't be included in the results as they appears in the future, and none of the date range of the absence are today.
Presumably I need an iterative sub-function running on each entry with today's date where the employeeID matches.
So based on what I believe you're asking, you want to return a list of the people that are off today and when they are expected back based on the holidays that you have recorded in the system, which should only work only on consecutive days.
SQL Fiddle Demo
Schema Setup:
CREATE TABLE EmployeeAbsence
([AbsenceID] int, [EmployeeID] int, [AbsenceDate] DATETIME)
;
INSERT INTO EmployeeAbsence
([AbsenceID], [EmployeeID], [AbsenceDate])
VALUES
(100, 10, '2014-11-11'),
(101, 10, '2014-11-12'),
(102, 10, '2014-11-13'),
(103, 10, '2014-11-14'),
(104, 10, '2014-11-15'),
(107, 21, '2014-11-11'),
(108, 21, '2014-11-12'),
(120, 05, '2014-11-11'),
(130, 15, '2014-11-20')
;
Recursive CTE to generate the output:
;WITH cte AS (
SELECT EmployeeID, AbsenceDate
FROM dbo.EmployeeAbsence
WHERE AbsenceDate = CAST(GETDATE() AS DATE)
UNION ALL
SELECT e.EmployeeID, e.AbsenceDate
FROM cte
INNER JOIN dbo.EmployeeAbsence e ON e.EmployeeID = cte.EmployeeID
AND e.AbsenceDate = DATEADD(d,1,cte.AbsenceDate)
)
SELECT cte.EmployeeID, MAX(cte.AbsenceDate)
FROM cte
GROUP BY cte.EmployeeID
Results:
| EMPLOYEEID | Return Date |
|------------|---------------------------------|
| 5 | November, 11 2014 00:00:00+0000 |
| 10 | November, 15 2014 00:00:00+0000 |
| 21 | November, 12 2014 00:00:00+0000 |
Explanation:
The first SELECT in the CTE gets employees that are off today with this filter:
WHERE AbsenceDate = CAST(GETDATE() AS DATE)
This result set is then UNIONED back to the EmployeeAbsence table with a join that matches EmployeeID as well as the AbsenceDate + 1 day to find the consecutive days recursively using:
-- add a day to the cte.AbsenceDate from the first SELECT
e.AbsenceDate = DATEADD(d,1,cte.AbsenceDate)
The final SELECT simply groups the cte results by employee with the MAX AbsenceDate that has been calculated per employee.
SELECT cte.EmployeeID, MAX(cte.AbsenceDate)
FROM cte
GROUP BY cte.EmployeeID
Excluding Weekends:
I've done a quick test based on your comment and the below modification to the INNER JOIN within the CTE should exclude weekends when adding the extra days if it detects that adding a day will result in a Saturday:
INNER JOIN dbo.EmployeeAbsence e ON e.EmployeeID = cte.EmployeeID
AND e.AbsenceDate = CASE WHEN datepart(dw,DATEADD(d,1,cte.AbsenceDate)) = 7
THEN DATEADD(d,3,cte.AbsenceDate)
ELSE DATEADD(d,1,cte.AbsenceDate) END
So when you add a day: datepart(dw,DATEADD(d,1,cte.AbsenceDate)) = 7, if it results in Saturday (7), then you add 3 days instead of 1 to get Monday: DATEADD(d,3,cte.AbsenceDate).
You'd need to do a few things to get this data into a usable format. You need to be able to work out where a group begins and ends. This is difficult with this example because there is no straight forward grouping column.
So that we can calculate when a group starts and ends, you need to create a CTE containing all the columns and also use LAG() to get the AbsenceID and EmployeeID from the previous row for each row. In this CTE you should also use ROW_NUMBER() at the same time so that we have a way to re-order the rows into the same order again.
Something like:
WITH
[AbsenceStage] AS (
SELECT [AbsenceID], [EmployeeID], [AbsenceDate]
,[RN] = ROW_NUMBER() OVER (ORDER BY [EmployeeID] ASC, [AbsenceDate] ASC, [AbsenceID] ASC)
,[AbsenceID_Prev] = LAG([AbsenceID]) OVER (ORDER BY [EmployeeID] ASC, [AbsenceDate] ASC, [AbsenceID] ASC)
,[EmployeeID_Prev] = LAG([EmployeeID]) OVER (ORDER BY [EmployeeID] ASC, [AbsenceDate] ASC, [AbsenceID] ASC)
FROM [HR_Absence]
)
Now that we have this we can compare each row to the previous to see if the current row is in a different "group" to the previous row.
The condition would be something like:
[EmployeeID_Prev] IS NULL -- We have a new group if the previous row is null
OR [EmployeeID_Prev] <> [EmployeeID] -- Or if the previous row is for a different employee
OR [AbsenceID_Prev] <> ([AbsenceID]-1) -- Or if the AbsenceID is not sequential
You can then use this to join the CTE to it's self to find the first row in each group with something like:
....
FROM [AbsenceStage] AS [Row]
INNER JOIN [AbsenceStage] AS [First]
ON ([First].[RN] = (
-- Get the first row before ([RN] Less that or equal to) this one where it is the start of a grouping
SELECT MAX([RN]) FROM [AbsenceStage]
WHERE [RN] <= [Row].[RN] AND (
[EmployeeID_Prev] IS NULL
OR [EmployeeID_Prev] <> [EmployeeID]
OR [AbsenceID_Prev] <> ([AbsenceID]-1)
)
))
...
You can then GROUP BY the [First].[RN] which will now act like a group id and allow you to get the start and end date of each absence group.
SELECT
[Row].[EmployeeID]
,MIN([Row].[AbsenceDate]) AS [Absence_Begin]
,MAX([Row].[AbsenceDate]) AS [Absence_End]
...
-- FROM and INNER JOIN from above
...
GROUP BY [First].[RN], [Row].[EmployeeID];
You could then put all that into a view giving you the EmployeeID with the Start and End date of each absence. You can then easily pull out the Employee's currently off with a:
WHERE CAST(CURRENT_TIMESTAMP AS date) BETWEEN [Absence_Begin] AND [Absence_End]
SQL Fiddle
Like another answer here, I'm going to create the leave intervals, but via a different method. First the code:
declare #today date = getdate(); --use whatever date here
with g as (
select *, dateadd(day, -1 * row_number() over (partition by employeeid order by absencedate), AbsenceDate) as group_number
from employeeabsence
) , leave_intervals as (
select employeeid, min(absencedate) as [start], max(absencedate) as [end]
from g
group by EmployeeID, group_number
)
select employeeid, [start], [end]
from leave_intervals
where #today between [start] and [end]
By way of explanation, we first put a date value into a variable. I chose today, but this code will work for any date passed in. Next, we create a common table expression (CTE) that will add on a grouping column to your table. This is the meat of the solution, so it bears some treatment. Within a given interval, the AbsenceDate increases at a rate of one day per row. row_number() also increases at a rate of one per row. So, if we subtract a row_number() number of days from the AbsenceDate, we'll get another (arbitrary) date. The key here is to realize that that arbitrary date will be the same for every row in the interval, so we can use it to group by. From there, it's just a matter of doing just that; get the min and max per interval. Lastly, we find what intervals contain #today.
I have data recording the StartDateTime and EndDateTime (both DATETIME2) of a process for all of the year 2013.
My task is to find the maximum amount of times the process was being ran at any specific time throughout the year.
I have wrote some code to check every minute/second how many processes were running at the specific time, but this takes a very long time and would be impossible to let it run for the whole year.
Here is the code (in this case check every minute for the date 25/10/2013)
CREATE TABLE dbo.#Hit
(
ID INT IDENTITY (1,1) PRIMARY KEY,
Moment DATETIME2,
COUNT INT
)
DECLARE #moment DATETIME2
SET #moment = '2013-10-24 00:00:00'
WHILE #moment < '2013-10-25'
BEGIN
INSERT INTO #Hit ( Moment, COUNT )
SELECT #moment, COUNT(*)
FROM dbo.tblProcessTimeLog
WHERE ProcessFK IN (25)
AND #moment BETWEEN StartDateTime AND EndDateTime
AND DelInd = 0
PRINT #moment
SET #moment = DATEADD(MINute,1,#moment)
END
SELECT * FROM #Hit
ORDER BY COUNT DESC
Can anyone think how i could get a similar result (I just need the maximum amount of processes being run at any given time), but for all year?
Thanks
DECLARE #d DATETIME = '20130101'; -- the first day of the year you care about
;WITH m(m) AS
( -- all the minutes in a day
SELECT TOP (1440) ROW_NUMBER() OVER (ORDER BY number) - 1
FROM master..spt_values
),
d(d) AS
( -- all the days in *that* year (accounts for leap years vs. hard-coding 365)
SELECT TOP (DATEDIFF(DAY, #d, DATEADD(YEAR, 1, #d))) DATEADD(DAY, number, #d)
FROM master..spt_values WHERE type = N'P' ORDER BY number
),
x AS
( -- all the minutes in *that* year
SELECT moment = DATEADD(MINUTE, m.m, d.d) FROM m CROSS JOIN d
)
SELECT TOP (1) WITH TIES -- in case more than one at the top
x.moment, [COUNT] = COUNT(l.ProcessFK)
FROM x
INNER JOIN dbo.tblProcessTimeLog AS l
ON x.moment >= l.StartDateTime
AND x.moment <= l.EndDateTime
WHERE l.ProcessFK = 25 AND l.DelInd = 0
GROUP BY x.moment
ORDER BY [COUNT] DESC;
See this post for why I don't think you should use BETWEEN for range queries, even in cases where it does semantically do what you want.
Create a table T whose rows represent some time segments.
This table could well be a temporary table (depending on your case).
Say:
row 1 - [from=00:00:00, to=00:00:01)
row 2 - [from=00:00:01, to=00:00:02)
row 3 - [from=00:00:02, to=00:00:03)
and so on.
Then just join from your main table
(tblProcessTimeLog, I think) to this table
based on the datetime values recorded in
tblProcessTimeLog.
A year has just about half million minutes
so it is not that many rows to store in T.
I recently pulled some code from SO trying to solve the 'island and gaps' problem, and the algorithm for that should help you solve your problem.
The idea is that you want to find the point in time that has the most started processes, much like figuring out the deepest nesting of parenthesis in an expression:
( ( ( ) ( ( ( (deepest here, 6)))))
This sql will produce this result for you (I included a temp table with sample data):
/*
CREATE TABLE #tblProcessTimeLog
(
StartDateTime DATETIME2,
EndDateTime DATETIME2
)
-- delete from #tblProcessTimeLog
INSERT INTO #tblProcessTimeLog (StartDateTime, EndDateTime)
Values ('1/1/2012', '1/6/2012'),
('1/2/2012', '1/6/2012'),
('1/3/2012', '1/6/2012'),
('1/4/2012', '1/6/2012'),
('1/5/2012', '1/7/2012'),
('1/6/2012', '1/8/2012'),
('1/6/2012', '1/10/2012'),
('1/6/2012', '1/11/2012'),
('1/10/2012', '1/12/2012'),
('1/15/2012', '1/16/2012')
;
*/
with cteProcessGroups (EventDate, GroupId) as
(
select EVENT_DATE, (E.START_ORDINAL - E.OVERALL_ORDINAL) GROUP_ID
FROM
(
select EVENT_DATE, EVENT_TYPE,
MAX(START_ORDINAL) OVER (ORDER BY EVENT_DATE, EVENT_TYPE ROWS UNBOUNDED PRECEDING) as START_ORDINAL,
ROW_NUMBER() OVER (ORDER BY EVENT_DATE, EVENT_TYPE) AS OVERALL_ORDINAL
from
(
Select StartDateTime AS EVENT_DATE, 1 as EVENT_TYPE, ROW_NUMBER() OVER (ORDER BY StartDateTime) as START_ORDINAL
from #tblProcessTimeLog
UNION ALL
select EndDateTime, 0 as EVENT_TYPE, NULL
FROM #tblProcessTimeLog
) RAWDATA
) E
)
select Max(EventDate) as EventDate, count(GroupId) as OpenProcesses
from cteProcessGroups
group by (GroupId)
order by COUNT(GroupId) desc
Results:
EventDate OpenProcesses
2012-01-05 00:00:00.0000000 5
2012-01-06 00:00:00.0000000 4
2012-01-15 00:00:00.0000000 2
2012-01-10 00:00:00.0000000 2
2012-01-08 00:00:00.0000000 1
2012-01-07 00:00:00.0000000 1
2012-01-11 00:00:00.0000000 1
2012-01-06 00:00:00.0000000 1
2012-01-06 00:00:00.0000000 1
2012-01-06 00:00:00.0000000 1
2012-01-16 00:00:00.0000000 1
Note that the 'in-between' rows don't give anything meaningful. Basically this output is only tuned to tell you when the most activity was. Looking at the other rows in the out put, there wasn't just 1 process running on 1/8 (there was actually 3). But the way this code works is that by grouping the processes that are concurrent together in a group, you can count the number of simultaneous processes. The date returned is when the max concurrent processes began. It doesn't tell you how long they were going on for, but you can solve that with an additional query. (once you know the date the most was ocurring, you can find out the specific process IDs by using a BETWEEN statement on the date.)
Hope this helps.
I have something like this:
SELECt *
FROM (
SELECT prodid, date, time, tmp, rowid
FROM live_pilot_plant
WHERE date BETWEEN CONVERT(DATETIME, '3/19/2012', 101)
AND CONVERT(DATETIME, '3/31/2012', 101)
) b
WHERE b.rowid % 400 = 0
FYI: The reason for the convert in the where clause, is because my date is stored as a varchar(10), I had to convert it to datetime in order to get the correct range of data. (I tried a bunch of different things and this worked)
I'm wondering how I can return the data I want every 4 hours during those selected dates. I have data collected approximately every 5 seconds (with some breaks in data) - ie data wasn't collected during a 2 hour period, but then continues at 5 second increments.
In my example I just used a modulo with my rowid - and the syntax works, but as I mentioned above there are some periods where data isnt collected so using logic like: if you take data every 5 seconds and multiple that by 4 hours you can approximately say how many rows are in between wont work.
My time column is a varchar column and is in the form hh:mm:ss
My ideal output is:
| prodid | date | time | tmp |
| 4 | 3/19/2012 | 10:00:00 | 2.3 |
| 7 | 3/19/2012 | 14:00:24 | 3.2 |
As you can see I can be a bit off (in terms of seconds) - I more so need the approximate value in terms of time.
Thank you in advance.
This should work
select prodid, date, time, tmp, rowid
from live_pilot_plant as lpp
inner join (
select min(prodid) as prodid -- is prodid your PK?? if not change it to rowid or whatelse is your PK
from live_pilot_plant
WHERE date BETWEEN CONVERT(DATETIME, '3/19/2012', 101) -- or whatever you want
AND CONVERT(DATETIME, '3/31/2012', 101) -- for better performance it is on the inner select
group by date,
floor( -- floor makes the trick
convert(float,convert(datetime, time)) -- assumes "time" column is a varchar containing data like '19:23:05'
* 6 -- 6 comes form 24 hours / 4 hours
)
) as filter on lpp.prodid = filter.prodid -- if prodid is not the PK also correct here.
A side note for everyone else who have date + time data in only one datetime field, suppose named "when_it_was", the group by can be as simple as:
group by floor(when_it_was * 6) -- again, 6 comes from 24/4
something along the lines of the following should work. Basically create date + time partitions, each partition representing a block of 4 hours and pick the record with the highest rank from each partition
select * from (
select *,
row_number() over (partition by date,cast(left( time, charindex( ':', time) - 1) as int) / 4 order by
date, time) as ranker from live_pilot_plant
) Z where ranker = 1
Assuming rowid is a PK and increased with date/time. Just convert time field to 4 hours interval number substring(time,1,2))/4 and select MIN(rowid) from each of 4 hours groups in a day:
select prodid, date, time, tmp, rowid from live_pilot_plant where rowid in
(
select min(rowid)
from live_pilot_plant
WHERE CONVERT(DATETIME, date, 101) BETWEEN CONVERT(DATETIME, '3/19/2012', 101)
AND CONVERT(DATETIME, '3/31/2012', 101)
group by date,convert(int,substring(time,1,2))/4
)
order by CONVERT(DATETIME, date, 101),time