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Selecting features with NULL attributes in QGIS

Geographic Information Systems Asked on July 15, 2021

How do I identify which features have NULL attributes in the attribute table of a shapefile?

When i try [field]= 'NULL' it selects the features with value = 0 (see picture)

example

4 Answers

Have you tried replacing the "=" with "is"? I don't have QGIS in front of me, but that is pretty common database select syntax for working with NULL values.

pedonal is NULL

Correct answer by RyanKDalton on July 15, 2021

Try:

Pedonal = ''

  • that should work!

Answered by Darren Cope on July 15, 2021

I beat my brains about this one. The field name is "ASSETID", it is either a value or NULL. But actually the field was a text field (KML). I tried..

"ASSETID" ISNULL, "ASSETID" IS NULL, ISNULL("ASSETID"), "ASSETID" = ""  NOTHING WORKED!

However

"ASSETID" = '', "ASSETID" IN ('') did work also for search "ASSETID" in ('2251', '4321' etc)

Archaic but workable.

Answered by John Groat on July 15, 2021

This video instructs you how to update these selected Null values from another shapefile (layer). https://youtu.be/O2hkvJjR2_s

Answered by Huynh Kosmos on July 15, 2021

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