How to Fill blank Fields with other column QGIS

Question

I have two columns of the same data and I want to unite

for example I have the column "pole_type" and "pole_type_" and sometimes one has values and some times the other

like seen in the photo

I want to get all the values in "pole_type_" into "pole_type" so I can delete the first

Iv'e used so far the following rules but not succeeded

IF(NULL,"pole_type_","pole_type")

or

IF("pole_type='',"pole_type_","pole_type")

and so on but I havn't came up with anything that works.

Assuming empty are blank, not NULL (your second example), try adding a second = and remove the space : IF("pole_type"=="","pole_type_","pole_type") — SMiller, Commented Oct 24, 2018 at 16:27
Are you able to perform a selection of your data (outside of the calculator) for either blank or NULL? An example of selecting for NULL is here: gis.stackexchange.com/questions/16134 — SMiller, Commented Oct 24, 2018 at 16:30
In the screenshots your column is called "/_pole_type" (with an underscore at the start) but your formulas use "pole_type_" (with an underscore at the end). — csk, Commented Oct 24, 2018 at 16:50

Hayden Elza · Accepted Answer · 2018-10-24 16:31:50Z

15

Welcome to the wonders of COALESCE. Try this:

COALESCE( "pole_type_" , "pole_type" )

It will return the first non-null value in a list. If they are all null, it will return null.

answered Oct 24, 2018 at 16:31

Hayden Elza

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Bhekani Khumalo · Accepted Answer · 2018-10-24 16:58:14Z

6

You can use:

CASE WHEN "pole_type" IS NULL THEN "pole_type_" ELSE "pole_type" END

answered Oct 24, 2018 at 16:58

Bhekani Khumalo

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Pescariz · Accepted Answer · 2018-10-31 14:29:23Z

1

Another way, less efective, but easy for new users like me, could be:

Select by expression "pole_type" is NULL

Then make your table editable and update field "pole_type" with "pole_type_", but only selected features.

answered Oct 31, 2018 at 14:29

Pescariz

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3 Answers 3