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…

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…

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…

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…

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…

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 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…

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,…