I have a layer to analyze and I want to create a thematic map with rule based feature. There is a strange behaviour. I want to find all objects with no data (NULL). All empty objects. The zero value for me is a value. I write:
namefield = ''
The result is zero but I have 47 objects with NULL value. This is an error. The strange behaviour is if I write:
namefield != ''
The result is 56 objects. This rule works. It is impossible to find objects with no data but qgis find only objects with a value.
Is this a bug or a feature?
It is a bug for me!
I use qgis 1.8