One PHP statement to use result of IF statement for assignment

I have a situation where I have a function that does some database retrieval and either returns a value or an error. I'd like to have a single statement that calls the function and depending on result either assigns the returned value or a default value.

Using the tenary operator I could do something like this:

$val=(getVal($param)!='error' ? getVal($param) : "default");

but I don't want to have to call getVal twice because it excutes database queries and is expensive on performance.

I could also do it in two statements, but if possible I just want one. Appreciate any help.