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NULL handling in QlikView

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hic
Former Employee
Former Employee

NULL handling in QlikView

Last Update:

Dec 19, 2018 5:56:17 AM

Updated By:

hic

Created date:

Jun 29, 2012 2:46:27 AM

Attachments
  • What is the difference between a NULL and a missing value?
  • How are NULLs propagated in expressions?
  • How does QlikView display NULLs?
  • How do I make NULLs selectable?
  • How do I search for NULLs?
  • Can NULLs be used in key fieds to link tables?
  • What is Ternary Logic?

 

These quesions and others are answered in this Technical Brief.
Thank you, mellerbeck and Matthew Fryer for idea and inspiration.

 

See also

The Importance of Nothing ,

NULL – The Invisible Nothing and

Finding NULL

 

HIC

 

2012-12-18: Fixed an error in the section about NULL propagation pertaining to relational operators. Added examples in the same section. /HIC

2012-12-20: Added information about ideographic space. Changed layout of some truth tables (images). /HIC

2013-04-46: Added section about How QlikView displays NULLs

2016-10-13: Corrected a sentence about the result of <Product = {}>

Labels (1)
Comments
Anonymous
Not applicable

Henric, I ran this script in Qlik Sense Desktop 3.1 SR3:

<Start of script>

Set NullInterpret = '';

NullPropagation:
Load *, X & Y as [X & Y], Text(X & Y) as [Text(X & Y)];
Load X, Y
Inline [
X, Y
,
0, 0
0, 1
1, 0
1, 1
, 0
, 1
1,
0,
] (delimiter is ',');

Set NullInterpret =;

<End of script>

This is the result I get, the last 4 records don't make sense, values in field [X & Y] appear to be invalid, it also appears that in order to have Null properly concatenated with a numeric, I'll always have to use Text function to wrap X & Y, Text(X & Y):

X,Y,X & Y,Text(X & Y)

,,,

0,0,00,00

0,1,01,01

1,0,10,10

1,1,11,11

,0,00,0

,1,01,1

1,,01,1

0,,00,0

Anonymous
Not applicable

Henric, can you please take a look at the sample loading script above which produces unexpected results.

Not applicable

Thanks Henric, fantastic post!

paulyeo11
Master
Master

Hi All

I have a question related to this topic.

Re: How to drill in missing value ?

Hope some one can share with how to drill in the null value.

Paul Yeo

luismadriz
Specialist
Specialist

Very helpful and informative. Many thanks!

alis2063
Creator III
Creator III

Thanks for this post make so easier with exploring all the points of nulll...

sergio0592
Specialist III
Specialist III
Thanks!
Version history
Last update:
‎2018-12-19 05:56 AM
Updated by:
Former Employee