i mysql case ifadesi kullanın 'VE' olabilir

örneğin:

$d = $mysqli->query("SELECT id_timeslot, date_book, id_beautician

     ,coalesce(thera_b, 'available') AS thera_b

    FROM ( SELECT t.id_timeslot, p.id_beautician, b.date_book

    , MAX(CASE b.id_beautician WHEN 2 THEN 'booked' THEN 'booked' ELSE NULL END 
       AND 
       CASE b.date_book WHEN '2011-01-04' THEN 'booked' ELSE NULL END) AS thera_b

    FROM timeslot as t
    LEFT JOIN bookslot as b ON b.id_timeslot = t.id_timeslot
    LEFT JOIN beautician as p ON p.id_beautician = b.id_beautician
        GROUP BY t.id_timeslot) AS xx");

ya da herhangi başka bir çözüm?