[thomas_w]

Zwei mögliche Lösungswege

a) WHERE erweitern mit IN()...

SELECT c.id AS c_id, 
       MAX(c.title) AS c_title, 
       MAX(a.title) AS a_titel, 
       MAX(a.modified) AS a_modified,
       MAX(a.publish_up) AS a_puplish_up,
       MAX(s.title) AS s_title, 
       MAX(s.id) AS s_id 
  FROM categories c 
  JOIN content a 
    ON a.catid=c.id
  JOIN sections s 
    ON c.section=s.id
WHERE s.id IN (3,4,5)
GROUP BY c.id
ORDER BY a_puplish_up DESC ;

b) Mehrere SQL verbinden mit UNION ALL

SELECT c.id AS c_id, 
       MAX(c.title) AS c_title, 
       MAX(a.title) AS a_titel, 
       MAX(a.modified) AS a_modified,
       MAX(a.publish_up) AS a_puplish_up,
       MAX(s.title) AS s_title, 
       MAX(s.id) AS s_id 
  FROM categories c 
  JOIN content a 
    ON a.catid=c.id
  JOIN sections s 
    ON c.section=s.id
WHERE s.id = 3
GROUP BY c.id

UNION ALL

SELECT c.id AS c_id, 
       MAX(c.title) AS c_title, 
       MAX(a.title) AS a_titel, 
       MAX(a.modified) AS a_modified,
       MAX(a.publish_up) AS a_puplish_up,
       MAX(s.title) AS s_title, 
       MAX(s.id) AS s_id 
  FROM categories c 
  JOIN content a 
    ON a.catid=c.id
  JOIN sections s 
    ON c.section=s.id
WHERE s.id = 4
GROUP BY c.id

UNION ALL

SELECT c.id AS c_id, 
       MAX(c.title) AS c_title, 
       MAX(a.title) AS a_titel, 
       MAX(a.modified) AS a_modified,
       MAX(a.publish_up) AS a_puplish_up,
       MAX(s.title) AS s_title, 
       MAX(s.id) AS s_id 
  FROM categories c 
  JOIN content a 
    ON a.catid=c.id
  JOIN sections s 
    ON c.section=s.id
WHERE s.id = 5
GROUP BY c.id


ORDER BY a_puplish_up DESC ;

Viel Erfolg!

Grüße
Thomas