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QlikView 11 for Developers

You're reading from   QlikView 11 for Developers This book is smartly built around a practical case study – HighCloud Airlines – to help you gain an in-depth understanding of how to build applications for Business Intelligence using QlikView. A superb hands-on guide.

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Product type Paperback
Published in Nov 2012
Publisher Packt
ISBN-13 9781849686068
Length 534 pages
Edition 1st Edition
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Toc

Table of Contents (23) Chapters Close

QlikView 11 for Developers
Credits
Foreword
About the Authors
Acknowledgements
About the Reviewers
www.PacktPub.com
Preface
1. Meet QlikView 2. Seeing is Believing FREE CHAPTER 3. Data Sources 4. Data Modeling 5. Styling Up 6. Building Dashboards 7. Scripting 8. Data Modeling Best Practices 9. Basic Data Transformation 10. Advanced Expressions 11. Set Analysis and Point In Time Reporting 12. Advanced Data Transformation 13. More on Visual Design and User Experience 14. Security Index

Ordering, peeking, and matching all at once


In the earlier sections, we have discussed three different functions commonly used in data transformation. We will now present a use case in which all three functions will complement each other to achieve a specific task.

The use case

We know that the IntervalMatch function makes use of closed intervals already defined in a table. What happens if all we have is a start date? To illustrate this scenario, look at the following screenshot:

As you can see, the End Date field has disappeared. However, there is a way for us to guess it and assign the corresponding value, based on the start date of the immediate following record. That is, if one record starts on 1-Feb-1998 and the immediate following starts on 1-Jan-2000, it means that the first interval ended on 31-Dec-1999, right?

In order for us to calculate the end date, we need to first sort the table values so that all corresponding records are contiguous, then "peek" at the start value from the next...

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