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catalogue 7, View and index 1. Improve query efficiency 2. View 2.1 definition and function of view 2.2 reasons and advantages of establishing view 2.3 use of views 3. Index 3.1 concept of index 3.2 functions and advantages of index 3.3 index and storage engine 3.4 classification of index 3.4.1 general index 3.4.2 unique index 3.4 ...

Introduction: starting from an example of data duplication in nailing real person authentication scenario, this paper analyzes that the reason is idempotent failure caused by concurrency, and leads to the concept of idempotent. Aiming at the idempotent problem in concurrent scenario, a feasible methodology for realizing idempotent is proposed. ...

1, The table structure in the existing database casemanage is shown in the following figure TABLENAME:afinfo Idnameagebirthsexmemo1Xu Hongguo371979-03-23malehigh school2Wang Fangfang261988-02-06femaleundergraduate3Xu Xiaosheng241990-04-02malemaster4Chen Xiao301984-09-12femaledoctor5Zheng Kai271987-12-30malejunior college 1) Please write s ...

Hello, everyone. I'm Mr. Tony, who only talks about technology and doesn't cut his hair. Today, we introduce an application CASE of CASE conditional expression, using the example table Click here to download. If the company is about to celebrate its 20th anniversary, it plans to distribute an anniversary gift to all employees. The rules for ...

reference https://eco.dameng.com/docs/zh-cn/app-dev/python-python.html https://eco.dameng.com/docs/zh-cn/start/python-development.html outline DMPython dmPython is a database access interface provided by DM and developed according to the API usage regulations in Python DB API version 2.0 dmPython implements these API s to enable Pyt ...

1. Vue advanced usage 1.1. Custom components After learning the Element component, we will find that the component is actually a custom label. For example, the encapsulation of. In essence, a component is a reusable Vue instance with a name, which can be defined by ourselves. Define format Vue.component(Component name, { props:Prope ...

1, Mybatis annotation development single table operation 1.1 common notes of mybatis In recent years, annotation development has become more and more popular. Mybatis can also use annotation development, so that we can reduce the writing of Mapper Mapping file. We first learn about some basic CRUD, and then learn about complex mapping ...

Database advanced After learning database related knowledge, please be sure to see the precautions. Precautions for database statements: https://blog.csdn.net/qq_43098690/article/details/121661835 1, Database integrity As the name suggests, the data stored in the database must be valid, that is, validity and accuracy. Ensure data int ...

Welcome to the MySQL technical articles shared by the great SQL community. If you have any questions or want to learn, you can leave a message in the comment area below. After seeing it, you will answer itproblemRun the following Python code, but you can't always update the data:import pymysql conn=pymysql.connect( host = '127.0.0.1', user = 'y ...

preface Interviewer: let's say, how do you query 10 million data? Brother B: direct paging query, using limit paging. Interviewer: have you practiced it? Brother B: there must be Here's a song "cool" Maybe some people have never met a table with tens of millions of data, and they don't know what will happen when querying tens o ...