BEGIN
DROP table if exists attendeesWithCustomFields;
SET @sql = NULL;
SELECT GROUP_CONCAT( DISTINCT
    	CONCAT(
			'MIN(CASE WHEN cf.field_name = ''',
			field_name,
			''' THEN cf.field_value END) AS ',
			field_name
    	)
  	) INTO @sql
FROM custom_fields;
SET @sql = CONCAT(	'CREATE TABLE attendeesWithCustomFields 
					SELECT a.* , ', @sql , '
	               FROM attendees a 
	               LEFT JOIN custom_fields AS cf
                    ON cf.event_id = a.event_id AND cf.investor_id = a.investor_id
					GROUP BY a.event_id, a.investor_id ' );
PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
END