NULL通过将其包装在空字符串中来转换值
COALESCE
SELECt CONCAt(COALESCE(`affiliate_name`,''),'-',COALESCE(`model`,''),'-',COALESCE(`ip`,''),'-',COALESCE(`os_type`,''),'-',COALESCE(`os_version`,'')) AS device_nameFROM devices

NULL通过将其包装在空字符串中来转换值
COALESCE
SELECt CONCAt(COALESCE(`affiliate_name`,''),'-',COALESCE(`model`,''),'-',COALESCE(`ip`,''),'-',COALESCE(`os_type`,''),'-',COALESCE(`os_version`,'')) AS device_nameFROM devices