SELECT
	`id`,
	`name`,
	`cellphone`,
	(
		SELECT `name` FROM `class` WHERE `id` = `student`.`class_id`
	) as `class_name`,
	(
		SELECT `type` FROM `class` WHERE `id` = `student`.`class_id`
	) as `class_type`
FROM `student`

------------------------------

SELECT
	`student`.`id`,
	`student`.`name`,
	`student`.`cellphone`,
	`class`.`name`,
	`class`.`type`
FROM `student`
INNER JOIN `class`
ON `student`.`class_id` = `class`.`id`