Just a little explanation for a beginner...

[eluser]Colin Williams[/eluser]
I would aim for a single JOIN query, but another option is to just run two queries and then iterate over one and do the logic in PHP to append artists to a property of the event objects. (Looks like all you are doing in your current code is converting object notation to array notation, and adding a dimension to the array)

Either way do it in your model. That way anytime your information/data needs change, you've got just one place to make changes to (the model).