Tag:New words

  • CSAPP English Learning Series: Preface

    Time:2021-10-17

    Series articles: CSAPP English Learning Series: Preface CSAPP English Learning Series: Chapter 1: a tour of computer systems CSAPP English Learning Series: Chapter 2: data representation CSAPP English Learning Series: Chapter 8: exceptional control flow CSAPP English Learning Series: Chapter 11: network programming CSAPP English Learning Series: Chapter 12: concurrent programming Reading CSAPP is based […]

  • MySQL data definition language (DDL)

    Time:2021-8-30

    Write in front In this paper[content]On behalf of ah, optional, you can write or not. Introduction to the basic functions of SQL language SQL is a structured query language with the following functions: Data definition language (DDL): full name: data definition language Data manipulation language (DML): full name: data manipulation language Data query language (DQL): […]

  • Mongodb aggregation classification

    Time:2020-6-25

    Add a set to store stock transactions db.transactions.insert([ { symbol: “600519”, qty: 100, price: 567.4, currency: “CNY” }, { symbol: “AMZN”, qty: 1, price: 1377.5, currency: “USD” }, { symbol: “AAPL”, qty: 2, price: 150.7, currency: “USD” } ]) Group by transaction currency db.transactions.aggregate([ { $group:{ _id:”$currency” } } ]) { “_id” : “CNY” } […]