Filling attribute table automatically but with specific values in QGIS 3.10

Question

I'm currently trying to built a database for a cocoa plantation. I would like to know how to fill my database easily with the field calculator. For example I would like to have a specific value for my field "Varieté", but not for all the column.

Is it possible to put the value "Upala Silva" only for the "ID" 1 to 70?

Answer 1

From Field Calculator, Check Update existing field, and select "Varieté" field. Then, you can use the following conditional statement in the field calculator:

case
when "ID" <= 70 then 'Upala Silva'
when ("ID" > 70  and "ID" <= 100) then 'bbbbb'
.
.
.
else 'ccccc'
end

The other conditions are just an example on how to add different ranges. Therefore, you may need to change "ID" <= 100 to a different value according to your needs. Don't forget to remove the dots if you don't have other conditions.

Answer 2

Additionally to ahmadhand's solution you may try using if-function.

if("ID" <= 70, 'Upala Silva', '')

function if

Tests a condition and returns a different result depending on the conditional check.

Syntax

if(condition,result_when_true,result_when_false)

Arguments

• condition the condition which should be checked
  
• result_when_true the result which will be returned when the condition is true or > another value that does not convert to false
  
• result_when_false the result which will be returned when the condition is false or another value that converts to false like 0 or ''. NULL will also be converted to false.

More about Conditional Functions you can find here.