题目标签: 题目给了我们一个 email 的table,让我们找到重复的 email. 可以建立 Person a, Person b, 找到两个表格中,emai 相等 但是 id 不同的 email, 然后利用DISTINCT 返回,因为两个表格中,会找到两个 重复的email. Java Solution: Runtime:  224 ms, faster than 40 % Memory Usage: N/A 完成日期:06/01/2019 关键点:用DISTINCT # Write yo…

题目标签: 题目给了我们一个 email 的表格,让我们删除重复的. 建立Person p1,Person p2,当email 相同时,而且 p1 id 要大于 p2 id 时候,删除这一行. Java Solution: Runtime:  869 ms, faster than 33 % Memory Usage: N/A 完成日期:06/01/2019 关键点:p1.Id > p2.Id # Write your MySQL query statement below DELETE p1…

182. 查找重复的电子邮箱 LeetCode_MySql_182 题目描述 方法一:使用笛卡尔积 # Write your MySQL query statement below select distinct t1.Email from Person t1, Person t2 where t1.Id != t2.Id and t1.Email = t2.Email; 方法二:使用group by 和临时表 select Email from ( select Email, count(Em…

Write a SQL query to find all duplicate emails in a table named Person. +----+---------+ | Id | Email | +----+---------+ | 1 | a@b.com | | 2 | c@d.com | | 3 | a@b.com | +----+---------+ For example, your query should return the following for the abov…

题目链接:https://leetcode-cn.com/problems/duplicate-emails/ 题目 编写一个 SQL 查询,查找 Person 表中所有重复的电子邮箱. 示例: +----+---------+ | Id | Email | +----+---------+ | 1 | a@b.com | | 2 | c@d.com | | 3 | a@b.com | +----+---------+ 根据以上输入,你的查询应返回以下结果: +---------+ | Emai…

编写一个 SQL 查询,查找 Person 表中所有重复的电子邮箱. 示例: +----+---------+ | Id | Email | +----+---------+ | 1 | a@b.com | | 2 | c@d.com | | 3 | a@b.com | +----+---------+ 根据以上输入,你的查询应返回以下结果: +---------+ | Email | +---------+ | a@b.com | +---------+ 说明:所有电子邮箱都是小写字母. 题解…

编写一个 SQL 查询,查找 Person 表中所有重复的电子邮箱. 示例: +----+---------+| Id | Email |+----+---------+| 1 | a@b.com || 2 | c@d.com || 3 | a@b.com |+----+---------+根据以上输入,你的查询应返回以下结果: +---------+| Email |+---------+| a@b.com |+---------+说明:所有电子邮箱都是小写字母. 来源:力扣(LeetCode…

Write a SQL query to delete all duplicate email entries in a table named Person, keeping only unique emails based on its smallest Id. +----+------------------+ | Id | Email | +----+------------------+ | 1 | john@example.com | | 2 | bob@example.com |…

Write a SQL query to find all duplicate emails in a table named Person. +----+---------+ | Id | Email | +----+---------+ | 1 | a@b.com | | 2 | c@d.com | | 3 | a@b.com | +----+---------+ For example, your query should return the following for the abov…

https://leetcode.com/problems/duplicate-emails/description/ 首先sql的执行顺序是 from-->where-->group by--->having-->select-->order by 所以用了group后,用where判断是错误的 # Write your MySQL query statement below select distinct Email //这里不需要distinct,因为group后,相同…

Write a SQL query to delete all duplicate email entries in a table named Person, keeping only unique emails based on its smallest Id. +----+------------------+ | Id | Email | +----+------------------+ | 1 | john@example.com | | 2 | bob@example.com |…

题目链接:https://leetcode-cn.com/problems/delete-duplicate-emails/ 题目 编写一个 SQL 查询,来删除 Person 表中所有重复的电子邮箱,重复的邮箱里只保留 Id 最小的那个. +----+------------------+ | Id | Email | +----+------------------+ | 1 | john@example.com | | 2 | bob@example.com | | 3 | john@ex…

题目 编写一个 SQL 查询,来删除 Person 表中所有重复的电子邮箱,重复的邮箱里只保留 Id 最小 的那个. +----+------------------+ | Id | Email | +----+------------------+ | 1 | john@example.com | | 2 | bob@example.com | | 3 | john@example.com | +----+------------------+ Id 是这个表的主键. 例如,在运行你的查询语句…

编写一个 SQL 查询,来删除 Person 表中所有重复的电子邮箱,重复的邮箱里只保留 Id 最小 的那个. +----+------------------+ | Id | Email | +----+------------------+ | 1 | john@example.com | | 2 | bob@example.com | | 3 | john@example.com | +----+------------------+ Id 是这个表的主键. 例如,在运行你的查询语句之后,…

编写一个 SQL 查询,来删除 Person 表中所有重复的电子邮箱,重复的邮箱里只保留 Id 最小 的那个. +----+------------------+ | Id | Email | +----+------------------+ | 1 | john@example.com | | 2 | bob@example.com | | 3 | john@example.com | +----+------------------+ Id 是这个表的主键. 例如,在运行你的查询语句之后,…

1.编写一个 SQL 查询,查找所有至少连续出现三次的数字. +----+-----+ | Id | Num | +----+-----+ | 1 | 1 | | 2 | 1 | | 3 | 1 | | 4 | 2 | | 5 | 1 | | 6 | 2 | | 7 | 2 | +----+-----+ 例如,给定上面的 Logs 表, 1 是唯一连续出现至少三次的数字. +-----------------+ | ConsecutiveNums | +-----------------+ |…

Write a SQL query to find all duplicate emails in a table named Person. +----+---------+ | Id | Email | +----+---------+ | 1 | a@b.com | | 2 | c@d.com | | 3 | a@b.com | +----+---------+ For example, your query should return the following for the abov…

Given an array of integers, find out whether there are two distinct indices i and j in the array such that the difference between nums[i] and nums[j] is at most t and the difference between i and j is at most k. 这道题跟之前两道Contains Duplicate 包含重复值和Conta…

Write a SQL query to find all duplicate emails in a table named Person. +----+---------+ | Id | Email | +----+---------+ | 1 | a@b.com | | 2 | c@d.com | | 3 | a@b.com | +----+---------+ For example, your query should return the following for the abov…

Write a SQL query to find all duplicate emails in a table named Person. +----+---------+ | Id | Email | +----+---------+ | 1 | a@b.com | | 2 | c@d.com | | 3 | a@b.com | +----+---------+ # Write your MySQL query statement below select Email from Perso…

Given an array of integers and an integer k, return true if and only if there are two distinct indices i and j in the array such that nums[i] = nums[j] and the difference between i and j is at most k. (Old Version) Given an array of integers and an i…

Given a binary tree, return all duplicate subtrees. For each kind of duplicate subtrees, you only need to return the root node of any oneof them. Two trees are duplicate if they have the same structure with same node values. Example 1: 1 / \ 2 3 / /…

Discription:Write a SQL query to delete all duplicate email entries in a table named Person, keeping only unique emails based on its smallest Id. 删除重复的Email地址,保留Id最小的那个. 使用自身连接循环即可. # Write your MySQL query statement below delete p1 from Person p1, P…

Write a SQL query to delete all duplicate email entries in a table named Person, keeping only unique emails based on its smallest Id. +----+------------------+ | Id | Email | +----+------------------+ | 1 | john@example.com | | 2 | bob@example.com |…

题意: 如果所给序列的元素不是唯一的,则返回true,否则false. 思路: 哈希map解决. class Solution { public: bool containsDuplicate(vector<int>& nums) { unordered_map<int,int> mapp; ; i<nums.size(); i++) { if(mapp[nums[i]]) return true; ; } return false; } }; AC代码 python…

Write a SQL query to find all duplicate emails in a table named Person. +----+---------+ | Id | Email | +----+---------+ | 1 | a@b.com | | 2 | c@d.com | | 3 | a@b.com | +----+---------+ For example, your query should return the following for the abov…

Write a SQL query to find all duplicate emails in a table named Person. +----+---------+ | Id | Email | +----+---------+ | 1 | a@b.com | | 2 | c@d.com | | 3 | a@b.com | +----+---------+ For example, your query should return the following for the abov…

Given an array of integers, find if the array contains any duplicates. Your function should return true if any value appears at least twice in the array, and it should return false if every element is distinct. 这道题不算难题,就是使用一个哈希表,遍历整个数组,如果哈希表里存在,返回fal…

Description:Write a SQL query to find all duplicate emails in a table named Person. 找出表中重复的Email. # Write your MySQL query statement below select Email from Person group by Email having count(*)>1;…

Given an array of integers and an integer k, find out whether there are two distinct indices i and j in the array such that nums[i] = nums[j] and the absolute difference between i and j is at most k. Example 1: Input: nums = [1,2,3,1], k = 3 Output:…