Wrong solution: Got 64,458 rows instead of 81,532 rows

****Retrieving Courses Information with SQL****

WITH title_total_minutes AS
(
SELECT
course_id,
course_title,
ROUND(SUM(minutes_watched), 2) AS total_minutes_watched,
COUNT(DISTINCT student_id) AS num_students
FROM
365_course_info
JOIN
365_student_learning USING (course_id)
GROUP BY course_id
),

title_average_minutes AS
(
SELECT
course_id,
course_title,
total_minutes_watched,
ROUND(total_minutes_watched/num_students, 2) AS average_minutes
FROM
title_total_minutes
),

title_ratings AS
(
SELECT
course_id,
course_title,
total_minutes_watched,
average_minutes,
COUNT(course_rating) AS number_of_ratings,
ROUND(SUM(course_rating)/COUNT(course_rating), 2) AS average_rating
FROM
title_average_minutes
LEFT JOIN
365_course_ratings USING (course_id)
GROUP BY course_id
)

SELECT
course_id,
course_title,
total_minutes_watched,
average_minutes,
number_of_ratings,
average_rating
FROM
title_ratings;

****Retrieving Purchases Information with SQL****

DROP VIEW IF EXISTS purchases_info;

CREATE VIEW purchases_info AS
SELECT
purchase_id,
student_id,
purchase_type,
date_purchased AS date_start,
CASE
WHEN purchase_type = 'Monthly' THEN
date_add(makedate(year(date_purchased), day(date_purchased)),
INTERVAL MONTH(date_purchased) MONTH)
WHEN purchase_type = 'Quarterly' THEN
date_add(makedate(year(date_purchased), day(date_purchased)),
INTERVAL MONTH(date_purchased)+2 MONTH)
WHEN purchase_type = 'Annual' THEN
date_add(makedate(year(date_purchased), day(date_purchased)),
INTERVAL MONTH(date_purchased)+11 MONTH)
END AS date_end
FROM
365_student_purchases;

****Retrieving Students Information with SQL****

SELECT
student_id,
student_country,
date_registered,
date_watched,
minutes_watched,
onboarded,
MAX(paid) AS paid
FROM
(SELECT
student_id,
student_country,
date_registered,
date_watched,
minutes_watched,
onboarded,
IF(date_watched BETWEEN p.date_start AND p.date_end, 1, 0) AS paid
FROM
(SELECT
i.student_id,
i.student_country,
i.date_registered,
l.date_watched,
IF(l.date_watched IS NULL, 0, ROUND(SUM(l.minutes_watched), 2)) AS minutes_watched,
IF(l.date_watched IS NULL, 0, 1) AS onboarded

FROM
365_student_info i
JOIN
365_student_learning l USING (student_id)
GROUP BY student_id, date_watched) a
LEFT JOIN
purchases_info p USING (student_id)) b
GROUP BY student_id, date_watched;