596. Classes More Than 5 Students Poblem: Please list out all classes which have more than or equal to 5 students. GROUP BY + Subquery 建表语句: create table 表名( //表名一般以 t_ 或 tbl_ 开始,且不能以数字开头 字段名1 数据类型, 字段名2 数据类型, … ); 可能存在重复记......
Can you solve this real interview question? Classes More Than 5 Students - Table: Courses +---+---+ | Column Name | Type | +---+---+ | student | varchar | | class | varchar | +---+---+ (stude
The students should not be counted duplicate in each course. Code #用distinct是因为有可能有学生多次选了该门课 SELECTclassFROMcoursesGROUPBYclassHAVINGCOUNT(DISTINCTstudent)>=5
WHERE子句中不能使用聚集函数,而HAVING子句中可以。 对于本题来说,考虑用聚合函数COUNT 来统计calss大于等于5的课程数,于是应该首先考虑将class分组(GROUP BY),在组内进行数量统计(HAVING COUNT),对于数量大于等于5的情况则SELECT出来,同时还要考虑同组内的student重复的情况,此时应该只计数一次(DISTINCT)。 SELECTclass...
花花酱 LeetCode 596. Classes More Than 5 StudentsBy zxi on April 2, 2018Problem 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 | +---+---+...
超过5名学生的课 LeetCode 关注 73992 2019.12.05发布于 未知归属地 官方题解 MySQL 方法一:使用 GROUP BY 子句和子查询【通过】 思路 先统计每门课程的学生数量,再从中选择超过 5 名学生的课程。 算法 使用GROUP BY 和COUNT 获得每门课程的学生数量。 MySQL SELECT class, COUNT(DISTINCT student) FROM course...
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: Should output: Note:The students should not...
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解答:COUNT与 DISTINCT组合使用,满足The students s...Leetcode数据库题解-596. Classes More Than 5 Students 题目地址:https://leetcode.com/problems/classes-more-than-5-students/ 题解:列出被5名及以上的学生选的课程。根据class进行分组,然后统计超过5名及以上学生选择课程。 ......
There is a tablecourseswith 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|...