I'm trying to change a field value by the next conditional SQL script from a PostGIS database in QGIS Field Calculator:

when "Field_1" = 'YES' then "Field_2" = 'True'
else "Field_2" = 'False'

but it returns NULL value.

I've tried with 't'and 'true' as well but it didn't work.

Is there anyone who knows how to solve it?

  • 2
    Try updating existing field "Field_2" with formula "Field_1"='YES', which will evaluate to true or false. Or change 'True' to TRUE and 'False' to FALSE – BERA Jun 20 '19 at 7:23
  • 2
    Note that often 'True' is the literal string "True", whereas True is the boolean value of truth. – til_b Jun 20 '19 at 7:45

If you update a field in QGIS Field calculator, just specify the value, don't then "Field_2" = something, just then something.

For your code, try :

  WHEN "Field_1" = 'YES' THEN True
  ELSE False
  • If this is a string field, shouldn't it be 'true' and 'false' (with single quotation marks)? Or will the expression builder understand true and false should be used as strings? – csk Jun 20 '19 at 15:48
  • they both worked as I tested them in a boolean virtual field. I guess as you do that if it's a string field 'true' or 'false'should come between quotation marks – Rodrigo Vargas Jun 20 '19 at 15:57

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