596. Classes More Than 5 Students

(資訊來自於leetcode 596 Classes More Than 5 Students)

超過 5 名學生的班級

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編寫一個 SQL 查詢來報告所有至少有五個學生的班級。

以任意順序返回結果表。

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The image file may be corrupted
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The image path is incorrect
The image format is not supported

解題方式：



select class 
from Courses   
group by class having count(*)>=5

解題解析：

要取得至少有5個學生的班級，這邊我們就會用到聚合函數，但是WHERE不能搭配聚合函數，因此我們這邊就需要用HAVING子句，使用在GROUP BY 後面。
(資訊來自於 HAVING 子句 (SQL HAVING Clause)