一、Rank Scores

Write a SQL query to rank scores. If there is a tie between two scores, both should have the same ranking. Note that after a tie, the next ranking number should be the next consecutive integer value. In other words, there should be no "holes" between ranks.

+----+-------+
| Id | Score |
+----+-------+
| 1 | 3.50 |
| 2 | 3.65 |
| 3 | 4.00 |
| 4 | 3.85 |
| 5 | 4.00 |
| 6 | 3.65 |
+----+-------+

For example, given the above Scores table, your query should generate the following report (order by highest score):+-------+------+

| Score | Rank |
+-------+------+
| 4.00 | 1 |
| 4.00 | 1 |
| 3.85 | 2 |
| 3.65 | 3 |
| 3.65 | 3 |
| 3.50 | 4 |
+-------+------+
分析:题意为 编写SQL对分数进行排序。如果两个分数相等,其排名应相同。注意在排名相等的分数之后,下一个排名的数值应该连续。换言之,排名之间不应该有“洞”(跳跃)。
思路:使用mysql的自定义变量。
# Write your MySQL query statement below
select Score,Rank from
(
SELECT Score,
CASE
WHEN @dummy <=> Score THEN @Rank := @Rank
ELSE @Rank := @Rank +1
END AS Rank,@dummy := Score as dummy
FROM
(SELECT @Rank := 0,@dummy := NULL) r,
Scores
ORDER BY Score DESC
) AS C

或者:

# Write your MySQL query statement below
SELECT Scores.Score, COUNT(Ranking.Score) AS RANK
FROM Scores
, (
SELECT DISTINCT Score
FROM Scores
) Ranking
WHERE Scores.Score <= Ranking.Score
GROUP BY Scores.Id, Scores.Score
ORDER BY Scores.Score DESC;

  

  

 

leetcode Database3的更多相关文章

  1. leetcode Database3(Nth Highest Salary<—>Consecutive Numbers<—>Department Highest Salary)

    一.Nth Highest Salary Write a SQL query to get the nth highest salary from the Employee table. +----+ ...

  2. 我为什么要写LeetCode的博客?

    # 增强学习成果 有一个研究成果,在学习中传授他人知识和讨论是最高效的做法,而看书则是最低效的做法(具体研究成果没找到地址).我写LeetCode博客主要目的是增强学习成果.当然,我也想出名,然而不知 ...

  3. LeetCode All in One 题目讲解汇总(持续更新中...)

    终于将LeetCode的免费题刷完了,真是漫长的第一遍啊,估计很多题都忘的差不多了,这次开个题目汇总贴,并附上每道题目的解题连接,方便之后查阅吧~ 477 Total Hamming Distance ...

  4. [LeetCode] Longest Substring with At Least K Repeating Characters 至少有K个重复字符的最长子字符串

    Find the length of the longest substring T of a given string (consists of lowercase letters only) su ...

  5. Leetcode 笔记 113 - Path Sum II

    题目链接:Path Sum II | LeetCode OJ Given a binary tree and a sum, find all root-to-leaf paths where each ...

  6. Leetcode 笔记 112 - Path Sum

    题目链接:Path Sum | LeetCode OJ Given a binary tree and a sum, determine if the tree has a root-to-leaf ...

  7. Leetcode 笔记 110 - Balanced Binary Tree

    题目链接:Balanced Binary Tree | LeetCode OJ Given a binary tree, determine if it is height-balanced. For ...

  8. Leetcode 笔记 100 - Same Tree

    题目链接:Same Tree | LeetCode OJ Given two binary trees, write a function to check if they are equal or ...

  9. Leetcode 笔记 99 - Recover Binary Search Tree

    题目链接:Recover Binary Search Tree | LeetCode OJ Two elements of a binary search tree (BST) are swapped ...

随机推荐

  1. Leetcode#109 Convert Sorted List to Binary Search Tree

    原题地址 跟Convert Sorted Array to Binary Search Tree(参见这篇文章)类似,只不过用list就不能随机访问了. 代码: TreeNode *buildBST( ...

  2. 使用jQuery动态加载js脚本

    动态加载Javascript是一项非常强大且有用的技术.这方面的主题在本站已经讨论了不少,我也经常会在一些个人项目上使用RequireJS和Dojo加载js.它们很强大,但有时候也会得不偿失.如果你使 ...

  3. 常用正则表达式(匹配URL/email/number)

    var URL_REGEXP = /^(ftp|http|https):\/\/(\w+:{0,1}\w*@)?(\S+)(:[0-9]+)?(\/|\/([\w#!:.?+=&%@!\-\/ ...

  4. HDU 3518 Boring counting(后缀数组,字符处理)

    题目 参考自:http://blog.sina.com.cn/s/blog_64675f540100k9el.html 题目描述: 找出一个字符串中至少重复出现两次的字串的个数(重复出现时不能重叠). ...

  5. Full GC有关问题学习分析(转载)

    网站持久代引发Full GC问题分析 现状: Dragoon(监控系统)的日报显示trade_us_wholelsale(美国wholesale集群),日均Young GC次数25w次左右,应用暂停2 ...

  6. ExtJs之Panel基本布局

    <!DOCTYPE html> <html> <head> <title>ExtJs</title> <meta http-equiv ...

  7. maven本地仓库.m2文件夹路径讲解

    Maven是一个项目管理工具,它包含了一个项目对象模型 (Project Object Model),一组标准集合,一个项目生命周期(Project Lifecycle),一个依赖管理系统(Depen ...

  8. 李洪强漫谈iOS开发[C语言-004]-开发概述程序设计语言程序编译过程

    汇编语言 指令用特定的名字来标记,这就是汇编语言 人比较容易看懂汇编语言 汇编直接和程序一一对应的 有汇编器把程序翻译成机器码 把高级语言编译成计算机识别的语言 程序编译过程 命令行 UNIX 系统中 ...

  9. Android SlidingMenu侧滑菜单使用

    把下载的侧滑菜单压缩包打开,会有一个library文件夹,在eclipse中import existing android code into workspace,导入library文件夹,并且选择作 ...

  10. RSS FEED的应用

    参考:http://inezha.com/help/feedrss 今天工作中遇到了一个知识是RSS FEED.当时觉得很奇怪,我们要这个干嘛用?RSS Feed就是一个xml文件.里面不包含数据,但 ...