User
  .joins(:clients)
  .joins('LEFT JOIN positions ON positions.client_id = clients.id')
  .select('users.*, SUM(CASE users.id WHEN clients.manager_id THEN 1 ELSE 0 END) as clients_count, '\
          'SUM(CASE positions.status WHEN 0 THEN 1 ELSE 0 END) as active_positions_count, '\
          'SUM(CASE positions.status WHEN 1 THEN 1 ELSE 0 END) as passive_positions_count')
  .having('SUM(CASE positions.status WHEN 0 THEN 1 ELSE 0 END) > 0 '\
          'OR SUM(CASE positions.status WHEN 1 THEN 1 ELSE 0 END) > 0')
  .group('users.id')

User
  .joins('INNER JOIN ('\
          'SELECT '\
            'clients.id, '\
            'clients.manager_id, '\
            'SUM(CASE WHEN positions.status = 0 THEN 1 ELSE 0 END) AS active_positions_count, '\
            'SUM(CASE WHEN positions.status = 1 THEN 1 ELSE 0 END) AS passive_positions_count '\
          'FROM clients '\
          'INNER JOIN '\
            'positions ON positions.client_id = clients.id AND positions.status IN (0, 1) '\
          'GROUP BY clients.id'\
        ') AS sums ON sums.manager_id = users.id')
  .select('users.*, '\
          'COUNT(sums.manager_id) AS clients_count, '\
          'CAST(SUM(sums.active_positions_count) AS BIGINT) AS active_positions_count, '\
          'CAST(SUM(sums.passive_positions_count) AS BIGINT) AS passive_positions_count')
  .group('users.id')