[Qgis-user] New objectid numbers after using DIFFERENCE

[Nicolas Cadieux]

Hi,

If you are using a geopackage, you are probably getting a message that 
the file cannot be saved as geopackage requires a unique id field.   You 
can open the field calculator and update the field using $id  for the 
unique ID field.  If you delete this unique ID field, it will be 
recreated correctly if you delete the field and save the file (if you 
save in a geopackage file format).  (I guess this also has the potential 
to corrupt the file so this would be a last chance option).  You can 
also use the  autoincremental field function found in processing if you 
don't have a unique id field.

Nicolas

On 2022-05-11 5:32 a.m., Keith Trees via Qgis-user wrote:
>
> Sent from Mail <https://go.microsoft.com/fwlink/?LinkId=550986> for 
> Windows
>
> Hi All
>
> I have two vector polygon layers, soil and native vegetation 
> respectively. I used vector-geoprocessing tools-Difference to get the 
> output of the soils that had no native vegetation.
>
> The problem is that there are now multiple polygons that share the 
> same objectid as they are remnants of an original polygon. This is 
> repeated through the layer.
>
> How can I renumber the objectids so each polygon has a unique value?
>
> I need to be able to identify each polygon and also calculate its area.
>
> Regards
>
> Keith
>
>
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-- 
Nicolas Cadieux
https://gitlab.com/njacadieux
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