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596. Classes With at Least 5 Students

SQL 50 · Sorting and Grouping (day 4). Decode it with the hints, solve it on LeetCode, then compare with the reference solution in MySQLPostgreSQL.

Your work

Status Notes Your solution (MySQLPostgreSQL)

Open one at a time. Try to finish with as few as you can.

1. What does one output row represent?

One class.

2. Approach

GROUP BY class HAVING COUNT(student) >= 5.

3. The trap

“At least” means >=.

Tested on MySQL 8.0 and PostgreSQL 16. Switch dialect at the top of the page.

Show the MySQLPostgreSQL solution

SELECT class
FROM Courses
GROUP BY class
HAVING COUNT(student) >= 5;