[Qgis-user] Query expression bugs with NULL Values

[José Carlos Martínez Llario]

Hi List,
Im using some data from OSM, I used this data directly from osm file and 
converted to shape file too. In both cases same results:

The layers has 4635 rows:

"amenity"  <>  'restaurant' returns 37
"amenity"  =  'restaurant'  returns 11


The layers has 48 NULL values, so it means that amenity"  <> 
'restaurant' does not take into account the null values.
Hope this is a bug and not the correct behaviour.

Im using QGIS 2.8.1

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PD: There are more weird results with the NULL syntax. for example:

THIS IS OK
"amenity" is not NULL returns 48
"amenity" is NULL returns  4587

THIS IS WRONG (if null values can not be treated as a text in the syntax 
it shouldnt work in both cases or throw some error)
"amenity" <> 'NULL' returns 48
"amenity"  =  'NULL'  returns 0   ????


cheers,

-- 
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José Carlos Martínez Llario
http://cartosig.upv.es

Producción Cartográfica y SIG.
Dpto. Ingeniería Cartográfica.
Univ. Politécnica de Valencia.
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