LC196 - Delete Duplicate Emails (Easy) 这是个简单题,但是涉及一些需注意的点: DELETE FROM table WHERE (subquery)的写法不可用: MySQL Error 1093 - Can't specify target table for update in FROM clausestackoverflow.com/questions/45494/mysql-error-1093-cant-specify-target-table-for-update-in-f...
update salarysetsex=char(ascii('m')+ascii('f')-ascii(sex));//f:70,0b 0100 0110//m:77,0b 0100 1101///后四位异或得到 0b 1011,再用结果异或就还原了update salarysetsex=char(ascii(sex)^0xb) 这是一道sql题,前两个方法是可以很容易想到的。但是后面两个需要对char和ascii这两个比较少见的...
代码语言:javascript 代码运行次数:0 运行 AI代码解释 +---+---+|Id|Email|+---+---+|1|john@example.com||2|bob@example.com|+---+---+ 提示: 执行 SQL 之后,输出是整个 Person表。 使用 delete 语句。 题意:在表中删除重复的数据,并且留下的必须是id最小的 一、表关联直接删除法 先将表关...
I am sure that this kind of questions must have been asked before, but failed to find anything by searching this site. My apologies in advance if I missed any similar questions. Is there anything in C...Why is shared mutability bad? I was watching a presentation on Java, and at one ...
题目:https://leetcode-cn.com/explore/interview/card/top-interview-questions-easy/1/array/25/ 题目描述: 给定一个非空整数数组,除了某个元素只出现一次以外,其余每个元素均出现两次。找出那个只出现了一次的元素。 说明: 你的算法应该具有线性时间复杂度。 你可以不使用额外空间来实现吗? 示例 1: 示例 .....
所以大家不要走我这个弯路,建议有了Easy的基础之后,就分Tag刷Medium。把dfs,bfs,tree, linkedlist, sliding window, binary search, stack, dynamic programming... 各刷个十几道,就差不多会了。另外Top 100 liked questions 这个里面的题都很有意思,像 @胡津铭 建议的一样,这里面的题我也刷了三四遍。刚开始...
There is a tablecourseswith columns: student and class Please list out all classes which have more than or equal to 5 students. For example, the table: +---+---+ | student | class | +---+---+ | A | Math | | B | English | | C | ...
Can you write a SQL query to find the biggest number, which only appears once. +---+ |num| +---+ | 8 | | 8 | | 3 | | 3 | | 1 | | 4 | | 5 | | 6 | For the sample data above, your query should return the following result: ...
| x | int | | y | int | | z | int | +---+---+ In SQL, (x, y, z) is the primary key column for this table. Each row of this table contains the lengths of three line segments. Report for every three line segments whether they can form a triangle. Return the result tabl...
LeetCode-SQL-Solutions Description The SQL 50 on LeetCode provided an extensive collection of SQL problems covering a wide range of concepts and techniques. This challenge included easy, medium and hard level questions from various topics like- Selects Basic Joins Basic Aggregate Functions Sorting an...