Classes More Than 5 Students

List out all classes which have more than or equal to 5 students.

Example 1:

Table: Person

+---------+------------+

| student | class      |

+---------+------------+

| A       | Math       |

| B       | English    |

| C       | Math       |

| D       | Biology    |

| E       | Math       |

| F       | Computer   |

| G       | Math       |

| H       | Math       |

| I       | Math       |

| A       | Math       |

+---------+------------+

Result:

+---------+

| class   |

+---------+

| Math    |

+---------+

Approach

Mysql

SELECT class FROM(

SELECT DISTINCT student, class FROM courses) as t 

group by class HAVING count(class)>=5

Oracle

SELECT class FROM(

SELECT DISTINCT student, class FROM courses) 

group by class HAVING count(class)>=5