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596. Classes More Than 5 Students
Description
Table: Courses
+++  Column Name  Type  +++  student  varchar   class  varchar  +++ (student, class) is the primary key (combination of columns with unique values) for this table. Each row of this table indicates the name of a student and the class in which they are enrolled.
Write a solution to find all the classes that have at least five students.
Return the result table in any order.
The result format is in the following example.
Example 1:
Input: Courses table: +++  student  class  +++  A  Math   B  English   C  Math   D  Biology   E  Math   F  Computer   G  Math   H  Math   I  Math  +++ Output: ++  class  ++  Math  ++ Explanation:  Math has 6 students, so we include it.  English has 1 student, so we do not include it.  Biology has 1 student, so we do not include it.  Computer has 1 student, so we do not include it.
Solutions
Solution 1: Grouping and Aggregation
We can use the GROUP BY
statement to group by class and then use the HAVING
statement to filter out the classes with a student count greater than or equal to $5$.

# Write your MySQL query statement below SELECT class FROM Courses GROUP BY 1 HAVING COUNT(1) >= 5;