SELECT *, GROUP_CONCAT(id ORDER BY startdatum ASC SEPARATOR '-') AS id, GROUP_CONCAT(titel_nl ORDER BY startdatum ASC SEPARATOR ' + ') AS titel_nl, GROUP_CONCAT(titel_en ORDER BY startdatum ASC SEPARATOR ' + ') AS titel_en, ( IF(einddatum = 0, startdatum + 60 * 60 * 24, einddatum + 60 * 60 * 24) - UNIX_TIMESTAMP( FROM_UNIXTIME(startdatum, '%Y-%m-%d') ) ) AS duration, (UNIX_TIMESTAMP( FROM_UNIXTIME(startdatum, '%Y-%m-%d') ) - 1623888000) AS offset FROM wf_activities WHERE ( startdatum >= 1623888000 OR einddatum >= 1623888000 ) AND weergeven_en =1 GROUP BY UNIX_TIMESTAMP( FROM_UNIXTIME(startdatum, '%Y-%m-%d') ) ORDER BY startdatum ASC