QGIS - Countif function

Question

I have a simple attribute table structured in this way:

Features	Attribute1	Attribute2	Attribute3	Attribute4	Count
F1	5	0	1	3	3
F2	0	0	0	4	1
F3	1	2	0	0	2
F4	12	4	6	9	4

And I need to populate the 'Count' field depending on how many attributes have a value different from 0. In Excel I would use a simple Countif function such as Countif(Attribute1:Attribute4; "<>0"). In QGIS I tried to use this:

COUNT(CASE WHEN Attribute1 <> 0 THEN 1 END) +
COUNT(CASE WHEN Attribute2 <> 0 THEN 1 END) +
COUNT(CASE WHEN Attribute3 <> 0 THEN 1 END) +
COUNT(CASE WHEN Attribute4 <> 0 THEN 1 END) +

but I don't get the right result.

Answer 1

This expression gives you what you need:

with_variable(
  'ar', array(Attribute1, Attribute2, Attribute3, Attribute4),
  array_length(@ar) - array_count(@ar, 0)
)

with_variable assigns the second argument to the first argument to use it in the third argument that is an expression.

ar = array(Attribute1, Attribute2, Attribute3, Attribute4)

array_length(@ar) returns the length of the array. array_count(@ar, 0) counts the number of occurrences of a given value in the array. And array_length(@ar) - array_count(@ar, 0) gives you the number of fields that are different from 0.