Concatenate five fields where some may be NULL

Question

I have a trench containing five types of ducts. I have created fields the trenches: Type1, Type2, Type3, ...

The values in each field are the numbers of each type of duct that the trench contains.

eg. lets say that one trench contains 2 ducts of type one and one duct of type 2, then I would like to label it something like this: 2xType1,Type2

The other types are NULL. How can I write a compact expression to handle this?

Answer 1

Maybe use something like the following:

replace(
if("Type 1" > 0 and "Type 2" > 0, "Type 1" || 'x Type1, ' || "Type 2" || 'x Type2', 
if("Type 1" = 0 or "Type 1" IS NULL, "Type 2" || 'x Type2', 
if("Type 2" = 0 or "Type 2" IS NULL, "Type 1" || 'x Type1', ''))), '1x', '')