peek()? generate a line based on previous

[kmarsden]

StudentID	Absence	FromDatetime	ToDatetime
1	Sick	01/01/2015 00:00:00	01/01/2015 23:59:59
1	Sick	04/01/2015 00:00:00	05/01/2015 23:59:59
1	Exam	07/01/2015 00:00:00	07/01/2015 23:59:59
2	Exam	07/01/2015 00:00:00	07/01/2015 23:59:59

LOAD

StudentID, Absence, FromDatetime, ToDatetime

FROM

$(vPath)\Diary.qvd
(qvd) ;

Hi, I have an issue where I'm trying to evaluate the above table to find instances where StudentID AND Absence are the same as the previously loaded line. When this occurs I need to generate a line of data for the same StudentID but with the following:

• an Absence of 'Attending'
• a FromDatetime of 1 second after the ToDatetime on the previously loaded line
• a ToDatetime of 1 second after the ToDatetime on the previously loaded line (i.e. the same as FromDatetime above)

I'm assuming peek() should be used to evaluate StudentID and Absence which I'm fine with. However, I'm struggling to generate the additional line whenever the criteria is met. Any help would be greatly appreciated...

Example of required output would be:

StudentID	Absence	FromDatetime	ToDatetime
1	Sick	01/01/2015 00:00:00	01/01/2015 23:59:59
1	Attending	02/01/2015 00:00:00	02/01/2015 00:00:00
1	Sick	04/01/2015 00:00:00	05/01/2015 23:59:59
1	Exam	07/01/2015 00:00:00	07/01/2015 23:59:59
2	Exam	07/01/2015 00:00:00	07/01/2015 23:59:59

[hic · Accepted solution]

Try

Load
   RowNo() as RowNo,
   StudentID,
   ShouldBeDuplicated,
   If(IterNo()=1 and ShouldBeDuplicated,'Attending',Absence) as Absence,
   If(IterNo()=1 and ShouldBeDuplicated,TimeStamp(Previous(ToDatetime)+1/24/60/60),FromDatetime) as FromDatetime,
   If(IterNo()=1 and ShouldBeDuplicated,TimeStamp(Previous(ToDatetime)+1/24/60/60),ToDatetime) as ToDatetime
   While IterNo() =1 or (IterNo()=2 and ShouldBeDuplicated);
Load *,
   StudentID=Previous(StudentID) and Absence=Previous(Absence) as ShouldBeDuplicated
  From … ;

HIC

[kmarsden]

This does exactly what I needed. I removed the "+1/24/60/60" from the FromDatetime and ToDatetime fields and it is spot on. Thank you Henric, you saved me pulling my hair out!