- from artist, album: The from clause
    now has two tables, which we want to join.
  
- where album.artist_id = artist.artist_id: Specifies
      how the tables are connected, (FK to PK).
  
- By listing the album and artist tables in
      the from clause, we have attributes from both tables.
  
- Ambiguous column names must be qualified.
  
- Unambiguous column names may be qualified.