Find maximum field attribute values

Question

I'm looking for a way to find the max number of four different fields and write that in a new column. I have managed to use the field calculator to "+" the different fields into a new, but when I'm trying the max command I get lost. some of the fields are empty.

I have written this statement:

max( 
(CASE WHEN  "mean" IS NOT NULL THEN "mean" ELSE 0 END),
(CASE WHEN  "_mean" IS NOT NULL THEN "_mean" ELSE 0 END),
(CASE WHEN  "mean_1" IS NOT NULL THEN "mean_1" ELSE 0 END),
(CASE WHEN  "max" IS NOT NULL THEN "max" ELSE 0 END),
)

Answer 1

You could try using this expression instead:

max( 
coalesce("mean", 0), 
coalesce("_mean", 0), 
coalesce("mean_1", 0), 
coalesce("max", 0) 
)