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preface This article focuses on the most commonly used query data SELECT statement in SQL language. text 1. SELECT * FROM data_ table; --> from clause FROM declares that the data source for retrieving data is the data table SELECT keyword, followed by the column name to be retrieved, * represents all columns, and the number of column ...

The core content of this article is data cleaning. Data cleaning The steps of data work should be: Data acquisitionData cleaningData analysisData visualization and modeling Therefore, in the last blog post, I said that the next blog post will talk about an important step in data analysis We should know that data cleaning is carried out for t ...

Java cultivation program -- the 73rd day of learning punch in Java (72nd day of punch in) I've been busy with digital experiment recently. If you have any questions about verilog, please exchange and learn First, simply query the previous content. Query the top 200 cities in the city table. After grouping according to the Countr ...

1, AHT20 realizes data acquisition of temperature and humidity 1. Brief description of I2C protocol layer (1) Communication process of I2C protocol These figures show the data packet sequence of SDA line when master and slave communicate. Where S represents the transmission start signal (S) generated by the I2C interface of the host. At t ...

1, Definition of tree A finite set composed of n (n > 0) nodes is an empty tree when n is equal to zero For any non empty tree, it has the following properties: 1. There is a special node in the tree that becomes the root, which is represented by r 2. Other nodes can be divided into m (M > 0) disjoint finite sets T1.T2.T3... Tm, in w ...

Process introduction CI/CD is a method to frequently deliver applications to customers by introducing automation in the application development phase. The core concepts of CI/CD are continuous integration, continuous delivery and continuous deployment. In this article, I will introduce the practice of automated build and release based on GitLa ...

  1. Brief description of osi seven-layer model and TCP/IP five-layer model   OSI Seven Layers   1. Physical Layer: Transfer data frames over a local area network, responsible for managing communication between computer communication devices and network media. Devices are: network card, network cable, hub, repeater, modem, etc.   2. Data Link L ...

Chapter 1 understanding network programming and sockets 1.1 understand network programming and sockets 1.1.1 network programming and socket overview Network programming: write programs to enable two networked computers to exchange data with each other. socket: a software device used for network data transmission. Network programming ...

Daily learning notes, including ES6, Promise, Node.js, Webpack, http principles, Vue family bucket, and updates to Typescript, Vue3 and common interview questions may follow. Looking at the previous article, we already know a little about the basic use of require and how it works. By learning the source code, we also have the following proble ...

Basic Ideas: Local Optimal - >Global Optimal Difficulty: Determine the best "what object" Simple questions: Find money: a total of x Yuan with a minimum of several pieces of money 100 yuan 50 yuan 10 yuan 5 yuan 1 yuan Idea: x divides 100, 50, 20, 10, 5, 1 Integer division adds up leetcode 455 Allocate cookies Suppose you're a ...