Store and compare previous data set

[#1]

Hi, i would like to ask it is possible to store the previous data set when there is new data set upload? will it override the old data? and if it is possible to store, can I compare the 2 data set ?? for example able to analysis the difference in the budget from the old data set. thanks:)

[swuehl]

Sure, you can store your current data to QVDs after each reload (at the end of your script) and then use these snapshot QVDs to run your analysis.

[#3]

Hi Swuehl, thanks for reply, could you give me an example or explain the QVD more details?

[MindaugasBacius]

Source for investigation:

http://www.quickintelligence.co.uk/qlikview-qvd-files/

QVD, QVW and QVX

[swuehl]

This explains how you can store all tables in your model to QVD:

Storing all tables in Qlikview file to QVD

Maybe what you want to achieve is something similar to an incremental load, so here is an example for that (also explained in the reference manual):

http://qlikviewcookbook.com/download/delta-load-template/

Some more details about QVDs:

QVD Questions and Answers | Qlikview Cookbook

[#6]

Hi Mindaugas,

Thank you for sharing the great blog

[#7]

Thanks for the links, I have learn how to store tables to QVD. But how can i use it to run my analysis?

For example, last month my data is:

Project	Start Date	End Date	Budget
A	1/7/2016	8/10/2017	1000
B	1/3/2016	1/9/2016	500
C	1/2/2016	1/8/2017	600
D	7/12/2016	1/8/2017	700
E	6/8/2016	1/3/2017	800
F	1/7/2016	1/11/2017	900

This month, i make changes:

Project	Start Date	End Date	Budget
A	1/7/2016	8/10/2017	1000
B	1/3/2016	1/9/2016	600
C	1/2/2016	1/9/2020	600
D	7/12/2016	1/8/2017	700
E	6/8/2016	1/3/2017	400
F	1/7/2016	1/11/2017	900

I would like to alert that there is change of date and compare the Budget between this 2 months in the dashboard.

[MindaugasBacius]

I suggest you to make a flag while storing the data into QVD.

Like every time you save data to QVD add new field today() as Indicator to the new table.

1. Load the QVD
2. Make changes to the data resident QVD.
3. Add Indicator.
4. Store to the same QVD.

In this scenario you will have the history.

[swuehl]

Maybe have a look at

How to compare 2 tables and put non-matching results?

[#10]

Hi Mindaugas,

Thanks for your suggestion. I am totally new to the concern of QVD. May I know how to make changes to the data resident QVD? and when I store to the same QVD, how to ensure that it will not override the previous data? Thank you:)