SQL merge startdate and endate - tsql

Question

I want to merge several start dates and enddates from a log event (so 1 row for one date).
Input table is:
Ord Desc2 Date_Time
--------------------------
0 Down 1/1/2014 ==> Not merged because no Up after
1 Down 1/2/2014 ==> Rows 1 and 2 should be merged
2 Up 1/3/2014
5 Down 1/4/2014 ==> Rows 5 and 12 should be merged
12 Up 1/6/2014
13 Up 1/7/2014 ==> Not merged because no Down before
So results I'm looking for would be:
Ord DesactivationDateTime ActivationDateTime
----------------------------------------------------
0 1/1/2014
1 1/2/2014 1/3/2014
5 1/4/2014 1/6/2014
13 1/7/2014
SQL Request I've found was this one but it only works for UP/Down couple:
SELECT EventsDesactivation.Ord
, EventsDesactivation.Desc2
, EventsDesactivation.Date_Time AS DesactivationDateTime
, MIN(EventsActivation.Date_Time) AS ActivationDateTime
FROM Journal AS EventsDesactivation
LEFT OUTER JOIN Journal AS EventsActivation
ON EventsActivation.Module=EventsDesactivation.Module --This is one of common rows not displayed in this sample...
WHERE
(EventsDesactivation.Desc2 = 'Down')
AND (EventsActivation.Desc2 = 'Up')
AND (EventsActivation.Ord > EventsDesactivation.Ord)
GROUP BY EventsDesactivation.Ord, EventsDesactivation.Desc2, EventsDesactivation.Date_Time
I'd appreciate if you helped me to find the solution!
My last idea was to do a crazy UNION ALL on couples and singles rows with a final GROUP BY...
Thanks for your help!
Regards,
François

Answer 1

This matches your sample data and expected results but I've got a nagging feeling I'm missing some edge case(s):
declare #t table (Ord int, Desc2 varchar(13),Date_Time date)
insert into #t(Ord,Desc2,Date_Time) values
(0 ,'Down','20140101'),
(1 ,'Down','20140102'),
(2 ,'Up','20140103'),
(5 ,'Down','20140104'),
(12 ,'Up','20140106'),
(13 ,'Up','20140107')
;With numbered as (
select Ord,Desc2,Date_Time,
ROW_NUMBER() OVER (ORDER BY Ord /* or date_time? */) as rn
from
#t
)
select
CASE WHEN n1.Desc2='Up' and n2.Desc2='Up' THEN n2.Ord ELSE n1.Ord END,
CASE WHEN n1.Desc2='Up' and n2.Desc2='Up' THEN NULL ELSE n1.Date_Time END,
CASE WHEN n1.Desc2='Down' and n2.Desc2='Down' THEN NULL ELSE n2.Date_Time END
from
numbered n1
full outer join
numbered n2
on
n1.rn = n2.rn - 1
where
not (n1.Desc2='Up' and n2.Desc2='Down')
Basically, we join each row with the row that logically comes after it. We ignore Up rows which are followed by Down rows. And then we just have to work out if it's Down,Up (normal), Down,Down (report the first row's values only) or Up,Up (report the second row's values only)
Result:
----------- ---------- ----------
0 2014-01-01 NULL
1 2014-01-02 2014-01-03
5 2014-01-04 2014-01-06
13 NULL 2014-01-07

Answer 2

I've applied your idea to my real world and it works perfectly in a stored procedure. Thanks for that!
BUT my SQL client doesn't support stored procedure... Shame on me!
So I decided to create a table function (with pamareters) to call this SQL code.
Unfortunately, I didn't find the way to use you intermediate numbered table (called Event in my use)...
I got following error on line ";WITH Events AS" :
==> select statements included whithin a function cannot return a data to a client.
Here is function code I've done:
CREATE FUNCTION fnSensorsDesactivations
(
#dateStartInString nvarchar(50) = '',
#dateEndInString nvarchar(50) = '',
#Unit nvarchar(50) = null,
#HoursToAddFromGMT int = -2,
#DesactivationEventsFilter nvarchar(50) = 'Validation et Désactivation%',
#BeforeDesactivationComment nvarchar(50) = 'Validation et Désactivation Capteur par ',
#AfterDesactivationComment nvarchar(50) = '. Commentaire : ',
#ActivationEventsFilter nvarchar(50) = 'Activation Capteur par%',
#BeforeActivationUsername nvarchar(50) = 'Activation Capteur par '
)
RETURNS #TableTempToReturn TABLE
(
-- Add the column definitions for the TABLE variable here
--Ord int,
Unit nvarchar(50),
Module nvarchar(255),
Module_Description nvarchar(255),
DésactivationQui nvarchar(255),
DésactivationDateTime nvarchar(255),
DésactivationMessage nvarchar(255),
ActivationQui nvarchar(255),
ActivationDateTime nvarchar(255)
)
AS
BEGIN
DECLARE #ExcludeOrds AS nvarchar(255) -- Must be comma separated and also at first and last character
DECLARE #dateStart AS datetime -- to cast datetime from string because Dream Report is not able to pass parameters with formulas
DECLARE #dateEnd AS datetime -- to cast datetime from string because Dream Report is not able to pass parameters with formulas
SET #ExcludeOrds=',,,,,,,,,'
IF #dateStartInString='' OR #dateEndInString=''
BEGIN
--Init dates from yesterday to today if they are null
SET #dateEnd=GETDATE()
SET #dateStart=DATEADD(year, -1, #DateEnd)
END
ELSE
BEGIN
--Convert datetime from string to datetime format + hours from GMT to follow local datetime settings
SET #dateEnd=DATEADD(hour, #HoursToAddFromGMT, CONVERT(datetime, #dateEndInString, 121))
SET #dateStart=DATEADD(hour, #HoursToAddFromGMT, CONVERT(datetime, #dateStartInString, 121))
END
IF #Unit IS NULL SET #Unit='WIP-BC2'
--Calculate positions/orders of differents Activation and desactivation events
;WITH Events AS -- Here is my SQL error: select statements included whithin a function cannot return a data to a client.
(
SELECT Ord, Unit, Module, Module_Description, Desc2, Date_Time,
ROW_NUMBER() OVER (ORDER BY Unit, Module, Ord) AS rn
FROM
EJournal.dbo.Journal
WHERE
Date_Time <= #dateEnd
AND Unit = #Unit
AND (Desc2 like #DesactivationEventsFilter
OR Desc2 like #ActivationEventsFilter)
--AND (Date_Time like #ActivationEventsFilter and Date_Time<=#dateStart)
AND CHARINDEX(CAST(Ord AS nvarchar), #ExcludeOrds,1)=0
)
--Depending on desactivation and activation orders, select good Events in Activation/descativation columns
SELECT
--n1.Ord,n2.Ord, n1.Desc2, n2.Desc2,
n1.Module
, n1.Module_Description
, CASE
WHEN n1.Desc2 like #ActivationEventsFilter AND n2.Desc2 like #ActivationEventsFilter
THEN ''
WHEN n1.Desc2 like #DesactivationEventsFilter AND (n2.Desc2 like #ActivationEventsFilter OR n2.Ord IS NULL)
THEN ISNULL(LEFT(SUBSTRING(n1.Desc2, LEN(#BeforeDesactivationComment)+2, 255 )
, CHARINDEX(#AfterDesactivationComment, SUBSTRING(n1.Desc2, LEN(#BeforeDesactivationComment)+2, 255)) - 1), '')
WHEN n1.Desc2 like #DesactivationEventsFilter AND (n2.Desc2 like #DesactivationEventsFilter OR n2.Ord IS NULL)
THEN ISNULL(LEFT(SUBSTRING(n1.Desc2, LEN(#BeforeDesactivationComment)+2, 255 ), '')
, CHARINDEX(#AfterDesactivationComment, SUBSTRING(n1.Desc2, LEN(#BeforeDesactivationComment)+2, 255)) - 1)
ELSE ''
END AS DésactivationQui
, CASE
WHEN n1.Desc2 like #ActivationEventsFilter AND n2.Desc2 like #ActivationEventsFilter
THEN ''
WHEN n1.Desc2 like #DesactivationEventsFilter AND (n2.Desc2 like #ActivationEventsFilter OR n2.Ord IS NULL)
THEN ISNULL(CONVERT(nvarchar, n1.Date_Time, 121), '')
WHEN n1.Desc2 like #DesactivationEventsFilter AND (n2.Desc2 like #DesactivationEventsFilter OR n2.Ord IS NULL)
THEN ISNULL(CONVERT(nvarchar, n1.Date_Time, 121), '')
ELSE ''
END AS DésactivationDateTime
, CASE
WHEN n1.Desc2 like #ActivationEventsFilter AND n2.Desc2 like #ActivationEventsFilter
THEN ''
WHEN n1.Desc2 like #DesactivationEventsFilter AND (n2.Desc2 like #ActivationEventsFilter OR n2.Ord IS NULL)
THEN ISNULL(SUBSTRING(n1.Desc2, CHARINDEX(#AfterDesactivationComment, n1.Desc2)+LEN(#AfterDesactivationComment), 255 ) , '')
WHEN n1.Desc2 like #DesactivationEventsFilter AND (n2.Desc2 like #DesactivationEventsFilter OR n2.Ord IS NULL)
THEN ISNULL(SUBSTRING(n1.Desc2, CHARINDEX(#AfterDesactivationComment, n1.Desc2)+LEN(#AfterDesactivationComment), 255 ) , '')
ELSE ''
END AS DésactivationMessage
, CASE
WHEN n1.Desc2 like #ActivationEventsFilter AND n2.Desc2 like #ActivationEventsFilter
THEN ISNULL(SUBSTRING(n2.Desc2, LEN(#BeforeActivationUsername)+2, 255 ),'')
WHEN (n1.Desc2 like #DesactivationEventsFilter OR n1.Ord IS NULL) AND n2.Desc2 like #ActivationEventsFilter
THEN ISNULL(SUBSTRING(n2.Desc2, LEN(#BeforeActivationUsername)+2, 255 ), '')
--WHEN n1.Desc2 like #DesactivationEventsFilter AND n2.Desc2 like #DesactivationEventsFilter THEN ''
-- THEN ''
ELSE ''
END AS ActivationQui
, CASE
WHEN n1.Desc2 like #ActivationEventsFilter AND n2.Desc2 like #ActivationEventsFilter
THEN ISNULL(CONVERT(nvarchar, n2.Date_Time, 121),'')
WHEN (n1.Desc2 like #DesactivationEventsFilter OR n1.Ord IS NULL) AND n2.Desc2 like #ActivationEventsFilter
THEN ISNULL(CONVERT(nvarchar, n2.Date_Time, 121),'')
--WHEN n1.Desc2 like #DesactivationEventsFilter AND n2.Desc2 like #DesactivationEventsFilter
-- THEN ''
ELSE ''
END AS ActivationDateTime
FROM
Events n1
FULL OUTER JOIN
Events n2
ON n1.rn = n2.rn - 1
AND n1.Unit=n2.Unit
AND n1.Module=n2.Module
WHERE NOT (n1.Desc2 like #ActivationEventsFilter AND n2.Desc2 like #DesactivationEventsFilter)
AND n1.Desc2 like #DesactivationEventsFilter
AND n1.Date_Time <= #dateEnd
--AND n2.Date_Time <= #dateEnd
AND (n2.Ord IS NULL OR n2.Date_Time>=#dateStart)
RETURN
END
Would you've a magic solution for it ?
Thanks again for your help!
François