SQL Functions: QUOTENAME - bzzzt!
If you try this yourself you will notice that the last column returns NULL. This is because the @ symbol is not a valid delimiter, so you cannot pass any character in to wrap it around the field.
All of the tables in AdventureWorks2014 are correctly formatted, so lets add one that isn't.
The below query is going to fail because we do not have a properly formatted table name.
Use the QUOTENAME function, and this will run correctly.