SELECT
  (SELECT COUNT(*) FROM Dieleyseis) AS everything,
  (SELECT COUNT(*) FROM Dieleyseis WHERE model = 'leon') AS single




SELECT
  count(t1.klidi) AS single,
  count(t2.klidi) AS everything
FROM Dieleyseis AS t1
  LEFT JOIN Dieleyseis AS t2 ON t1.klidi = t2.klidi AND t2.model ="leon"