In QGIS 2.8 I have a large data set and I would like to search one field for any values over a certain amount (in this case 20) and if the value is larger than 20, I would like to return a value of 1 in another field, otherwise return a value of 0.
How can I implement it?
The most simple way to do this is to create a new field with the expression
"cat" > 20
This expression will evaluate to a boolean True/False which will be represented as an integer 1 or 0.
You can also create a virtual field, which will automatically return an updated value in case the values in cat change (e.g. you edit the layer). Remember that the values of virtual fields will not be saved in the dataset and are only visible inside this QGIS project.
If you have more than a simple "greater than", you need to use
CASE
WHEN "cat" > 100 THEN 2
WHEN "cat" > 10 THEN 1
ELSE 0
END
I just tested this : You can use the condition several times:
WHEN cat = 1 THEN 205
WHEN cat = 2 THEN 215
WHEN cat = 3 THEN 225
WHEN cat = 4 THEN 235
...
....
Something like this perhaps:
case
when "FIELD" > 20 then 1
else 0
end
