You could of course use key.split(",") , but you might want to find out why your multi-value key is being returned as a single string. Are you "@implode"ing the value in your view? Is the original field really multi-value or is it just a comma delimited string?

 

I tend to use the non-"@" formula methods (such as database.getView("viewName").getEntryByKey(keyValue)) as they are a bit more transparent and easier to debug.  Under the hood, @DbLookup is doing the same thing, but the direct methods give you access to intermediate components to check if everything is as you expect.

 

Rich