秋招学习数据库LeetCode刷题-编程知识

秋招学习数据库LeetCode刷题

数据库基本知识以前学过次数较多，今天看完一遍后都是可以理解的。直接刷Leetcode题吧
牛客上题库刷基础，Leetcode刷写语句题(争取坚持每日2个sql语句题)


牛客：https://www.nowcoder.com/exam/intelligent?questionJobId=10&tagId=21015
Leetcode：https://leetcode.cn/problems/second-highest-salary/description/

20240403

1.第二高的薪水

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select  max(salary) as SecondHighestSalary
from Employee 
where salary<(select max(salary) from Employee)

2.第N高薪水

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CREATE FUNCTION getNthHighestSalary(N INT) RETURNS INT
BEGIN
DECLARE M INT; SET M = N-1; RETURN (SELECT DISTINCT salaryFROM EmployeeORDER BY salary DESCLIMIT M, 1);
END

美妙！！！limit这个函数是想不到是这样用，思路灵活好重要

178.分数排名

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select score,dense_rank() over(order by score desc) as "rank"
from Scores
order by score desc;

180.连续出现的数字

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selectdistinct t.num as ConsecutiveNums 
from
(select id,num,row_number() over(order by id) as rn,row_number() over(partition by num order by id) as id_rnfrom Logs 
) t
group by t.num, (t.rn - t.id_rn)
having count(1) >= 3
;