refactor 596

Author: fishercoder1534

database/_596.sql

@@ -1,36 +1,3 @@
---596. Classes More Than 5 Students
---SQL Schema
---There is a table courses with columns: student and class
---
---Please list out all classes which have more than or equal to 5 students.
---
---For example, the table:
---
---+---------+------------+
---| student | class      |
---+---------+------------+
---| A       | Math       |
---| B       | English    |
---| C       | Math       |
---| D       | Biology    |
---| E       | Math       |
---| F       | Computer   |
---| G       | Math       |
---| H       | Math       |
---| I       | Math       |
---+---------+------------+
---Should output:
---
---+---------+
---| class   |
---+---------+
---| Math    |
---+---------+
---
---
---Note:
---The students should not be counted duplicate in each course.
-
 select class from courses
 group by class
 having count(distinct student) >= 5;