I was going through some sample codes around the web, and found that backticks (`) are sometimes used to enclose the table names and field names we used in the queries in DataObject:get and DataObject:get_one methods. For example:
I'm not sure if that's the case now but in older versions of SS you needed the backticks in order for the framework to keep track of which table to actually fetch from depending on if you're on the draft or the published site. This is of course only relevant for versioned objects and primarily SiteTree and its descendants.
You should really be using double quotes (") rather than back ticks (`) as back ticks are MySQL only and sapphire is designed to be database agnostic. This is especially important if you're releasing code as a module.
Also, you should always quote database, table and column names. Once again this is mostly to be database agnostic, though there is also the possibility that in a future version of your current RDBMS, one of these names could become a reserved keyword, or you RDBMS may start treating any non-quoted string as a literal string.