MySQL CONCAT returnerer NULL, hvis et felt indeholder NULL

konverter NULL værdier med tom streng ved at pakke den ind i COALESCE

SELECT CONCAT(COALESCE(`affiliate_name`,''),'-',COALESCE(`model`,''),'-',COALESCE(`ip`,''),'-',COALESCE(`os_type`,''),'-',COALESCE(`os_version`,'')) AS device_name
FROM devices