CUBE的用法和Postgres数组了解一下。 {代码...} prod users tally A {1,2,3} 3 A B {1,2} 2 A B C {2} 1 A B D {1} 1 A C {2} 1 A D {1} 1 B {1,2} 2 B C {2} 1 B D {1} 1 C {2} 1 D {1} 1

我要用select * from xxx where a in () 在前端一次传入N个设备，所以是这样： select * from xxx where a in ('a','b','c'); 现在是这样select * from xxx where a in ('a,b,c'); 怎么写

根据题主对问题描述的更新，Y是否可分为两部分分别处理： Y中a, b, c已经包含于X，则直接取X.d； 将Y去除满足 (1) 的行后，剩下的部分按a, b排序并取序号。注意此序号须跳过X中对应同样a, b的d的最大值。 {代码...}

有一种我不太熟悉的 ANSI 语法，还有一种我通常使用的 Oracle 语法。 Oracle 语法使用 CONNECT BY ... PRIOR 子句来构建树，并使用 START WITH 子句告诉数据库从何处开始遍历树。它看起来像这样：

A是数据表共有30万条数据，b,c,d 是字段，我给b和c，d分别加了index索引 执行 {代码...} 用时41.7ms（实际体验很慢） 结果： select_type table type possible_key key key_len ref rows Extra SIMPLE A index_merge b,c b,c 6,4 NULL 55577 Using intersect(region,cheat); Using where; Using filesort 请问我该怎么优化

题目：Clone an undirected graph. Each node in the graph contains a label and a list of its neighbors.

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{代码...} 但正如上面所说的，这里没必要用exec，直接取值就可以 {代码...}

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1.数据表有三个 {代码...} 2.想查询A的a和C的d字段。3.请输入代码 {代码...} 4.不会SQL，求指教下

KIT205 Data Structures and AlgorithmsAssignment 1: Data StructuresDue: 26th April, 11:55pmIntroductionYou work for an online marketing company that manages a number of store loyalty programs.You have been asked to develop some software to manage the customer database. Youdecide to develop a proto...

CS530, Spring 2019, Program Assignment #226 Feb 2019You and your team shall develop, test, and deliver a disassembler program for theXE variant of the SIC/XE family of machines.XE DISASSEMBLER REQUIREMENTS:The XE disassembler program shall open an XE object file, <filename>.obj and itsaccom...

子查询 {代码...}

为了理解该机制，我做了实验： {代码...} 编译成果返回 {代码...} (int *) e = &a, f = &b; 为什么行不通？

有用or的可以考虑换成用union来尝试下 {代码...}

{代码...} 这种方式能用到t列上的索引。

CSCI 5521: Machine Learning Fundamentals (Spring 2022)Quiz 1 (Thursday, Feb 10)Due on Gradescope at 02:00 PM, Friday, Feb 11Instructions: This quiz has 3 questions, 30 points, on 1 page. Please write your name & ID on your submission pages.