text: SELECT  m.Name, COUNT(il.InvoiceLineId) as TimesBought
  FROM Invoice i
  INNER JOIN InvoiceLine il
  ON i.InvoiceId = il.invoiceId
  INNER JOIN Track t
  ON il.TrackId = t.TrackId
  INNER JOIN MediaType m
  ON t.MediaTypeId = m.MediaTypeId
  GROUP BY m.Name
  ORDER BY TimesBought DESC LIMIT 1;
  