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# Can you please chech my solution?

Hi!

I did this:

```SELECT subjects.name, COUNT(students.id) AS "Number of Students" FROM students
INNER JOIN schedule ON students.id = schedule.student_id
INNER JOIN classes ON schedule.class_id = classes.id
INNER JOIN subjects ON classes.subject_id = subjects.id
GROUP BY subjects.name
ORDER BY "Number of Students"
LIMIT 1;
```

But before limiting the results to 1 I've got different results than on the video. For example on math I've got 512 students. Can you please check it? Thank you!

STAFF

Hey György!

The difference is from grouping on SUBJECTS.NAME instead of SUBJECTS.ID. The SUBJECTS table uses a second GRADE column to distinguish between the 3 grade levels of a subject. So instead of seeing 6th, 7th, and 8th grade math as 3 separate subjects, they all end up just being 'Math'.

Yes, in agreement with what Mr. Ben said, but with a minor tweak: I believe he had meant to say the difference between `GROUP BY SUBJECTS.ID` vs `GROUP BY CLASS_ID` -- the latter would result in 13 students in the smallest of the Puppetry classes, which is answering a slightly different question.

To clarify, there is no difference among the following three options:

```... GROUP BY SUBJECTS.NAME
... GROUP BY SUBJECTS.ID
... GROUP BY SUBJECT_ID
```

Ben, thank you for this video clarification -- I had originally run a `GROUP BY CLASS_ID`! :)

Here is a cleaner version but follows more or less the flow of the video:

```WITH COMMON_EXPRESSION AS (
SELECT DISTINCT(subjects.name) AS "Least Attended Class", COUNT(schedule.class_id) AS "Student Enrollment" FROM SUBJECTS
JOIN CLASSES ON subjects.id = classes.subject_id
JOIN SCHEDULE ON classes.id = schedule.class_id
GROUP BY classes.subject_id
)

SELECT "Least Attended Class", MIN("Student Enrollment") AS "Students Currently Enrolled" FROM COMMON_EXPRESSION;
```

Hope that helps!