Book Image

QlikView for Developers Cookbook

By : Stephen Redmond
Book Image

QlikView for Developers Cookbook

By: Stephen Redmond

Overview of this book

QlikView has been around since 1993, but has only really taken off in recent years as a leader in the in-memory BI space and, more recently, in the data discovery area. QlikView features the ability to consolidate relevant data from multiple sources into a single application, as well as an associative data model to allow you to explore the data to a way your brain works, state-of-the-art visualizations, dashboard, analysis and reports, and mobile data access. QlikView for Developers Cookbook builds on your initial training and experiences with QlikView to help you become a better developer. This book features plenty of hands-on examples of many challenging functions. Assuming a basic understanding of QlikView development, this book provides a range of step-by-step exercises to teach you different subjects to help build your QlikView developer expertise. From advanced charting and layout to set analysis; from advanced aggregations through to scripting, performance, and security, this book will cover all the areas that you need to know about. The recipes in this book will give you a lot of the information that you need to become an excellent QlikView developer.
Table of Contents (19 chapters)
QlikView for Developers Cookbook
Credits
Foreword
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

Creating flag fields to avoid Sum of If and other inefficient expressions


The more efficient our expressions are, the more efficient the whole document will be – especially where those expressions are used frequently.

Many times, with a more complex expression, just thinking about what is happening might lead you to come up with a flag field that could be precalculated in the script.

Calculation of a flag field does add extra time to the load script. It can also increase the size of the data set. But they are a lot quicker on the front-end, and that makes the document more efficient for users.

Getting ready

Generate QVDs created in the Reducing the number of distinct values recipe.

How to do it…

Follow these steps to create flag fields to avoid Sum of If expression and other inefficient expressions:

  1. Create a new QVW file in the same folder as QVDs and load the following script:

    Calendar:
    LOAD DateID, 
         Date, 
         If(Year2Date(Date, 0, 1, Today()), 1, 0) As YTDFlag,
         Year, 
         Month, ...