Dotaz tří spojených tabulek se vztahem many-to-many v JPA

Myslím, že váš SQL by mohl vypadat nějak takto:

SELECT * FROM Hospital WHERE Postcode = 3000 AND
Hospital_id IN
    (SELECT Hospital_id FROM Hospital_Medical hm
    INNER JOIN Medical_Service m ON hm.Medical_id = m.Medical_id
    where Medical_name = 'Emergency') AND
Hospital_id IN
(SELECT Hospital_id FROM Hospital_Language hl
    INNER JOIN Language_Service l ON hl.Language_id = l.Language_id
    where Language_name = 'English')