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Fall Semester Census

easySQLFilteringAggregation

Term-time staffing at Fairhaven University is driven by teaching load, and the load for a term is the number of sittings recorded against it — one student in one course counts as one sitting, so a student taking three courses puts three units of work into the term. The planning office is closing the books on the Fall2023 term and needs that figure.

A sitting counts whether or not a mark has been entered against it. Teaching happened either way, and some marks are still outstanding when the books close.

enrollments — one row per sitting: one student taking one course in one term. student_id points at a row in students and course_id at a row in courses. grade is the mark for that sitting, on the same 0-4 scale, and is NULL when no mark has been entered yet. semester is the term the sitting belongs to.

student_id course_id grade semester
1 1 3.7 Fall2023
1 2 3.9 Spring2024
2 1 3.2 Fall2023
2 3 3.5 Fall2023
3 2 4.0 Spring2024
3 4 3.8 Spring2024
4 3 2.9 Fall2023
5 1 3.6 Fall2023
5 2 NULL Spring2024

The table already exists in the database — there is nothing to create or load.

Task: Write a query that returns one row with one column, fall_enrollments, holding the number of sittings recorded for the term Fall2023. A sitting with no mark entered still counts.

Example output

If eighty-eight sittings had been recorded for that term, the single row would read:

fall_enrollments
88

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