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+ /*
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+ Classes More Than 5 Students
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+ https://leetcode.com/problems/classes-more-than-5-students/
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+
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+ There is a table courses with columns: student and class
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+
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+ Please list out all classes which have more than or equal to 5 students.
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+
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+ For example, the table:
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+
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+ +---------+------------+
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+ | student | class |
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+ +---------+------------+
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+ | A | Math |
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+ | B | English |
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+ | C | Math |
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+ | D | Biology |
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+ | E | Math |
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+ | F | Computer |
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+ | G | Math |
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+ | H | Math |
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+ | I | Math |
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+ +---------+------------+
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+ Should output:
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+
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+ +---------+
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+ | class |
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+ +---------+
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+ | Math |
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+ +---------+
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+
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+
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+ Note:
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+ The students should not be counted duplicate in each course.
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+ */
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+
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+ SELECT class
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+ FROM courses
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+ GROUP BY class
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+ HAVING count (DISTINCT(student)) > 4
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