1. 题目

exams 表中存放着同学们的考试记录
请用 SQL 语句，找到挂科数最多的同学所对应的 student_id

https://www.lintcode.com/problem/1932

2. 解题

-- Write your SQL Query here --
-- example: SELECT * FROM XX_TABLE WHERE XXX --
select student_id from
(select sum(if(is_pass=0, 1, 0)) ct, student_id from examsgroup by student_idhaving ct > 0order by ct desclimit 1
) t

• LintCode 1933， 挂科数目最多的同学 有多位

-- Write your SQL Query here --
-- example: SELECT * FROM XX_TABLE WHERE XXX --
select student_id from 
(select sum(if(is_pass=0, 1, 0)) ct, student_id from examsgroup by student_idhaving ct > 0
) t2
where ct in 
(select max(ct) from (select sum(if(is_pass=0, 1, 0)) ct, student_id from examsgroup by student_idhaving ct > 0)t2
)

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