Help with this query dealing with aggregates
First your query is missing a join on the two tables involved. After that, it can be slightly altered to get you the albums of bands with more than one album, like this:

SELECT b.name, alb.title                     -- show me all bands 
FROM band AS b                               -- and their albums
  JOIN album AS alb                          
    ON alb.band_id = b.band_id    
WHERE EXISTS                                 -- where exists at least one
      ( SELECT *    
        FROM album AS al                     -- other album
        WHERE al.band_id = alb.band_id       -- of the same band
          AND al.album_id &lt;&gt; alb.album_id    -- (this ensures the "other")
      ) ;