题解 | #商品交易(网易校招笔试真题)#

```SELECT
	b.course_id,
	c.course_name,
	ROUND( SUM( if_sign ) * 100 / COUNT( if_vw ), 2 ) AS 'sign_rate(%)' 
FROM
	behavior_tb b
	LEFT JOIN course_tb c ON b.course_id = c.course_id 
WHERE
	b.if_vw = 1 
GROUP BY
	b.course_id,
	c.course_name 
ORDER BY
	course_id ASC;