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mysql8.0 official website: processing group by 1. Initial conditions Now there is a table with two pairs of name = pants 2. Phenomenon Execute the following sql to get the data grouped by name: GROUP BY name SELECT name,author,SUM(price) FROM `t_book` GROUP BY name 1055 exception occurred while executing sql SELECT name,author,SUM ...

Write in front I see it in the book. Take it out and tidy it up separately. Generally, it is cluster deployment. Sometimes learning K8s is too heavy and I don't know how to start:Here I hope to have a preliminary understanding of K8S through my blog.The content of the blog includes: Setup of stand-alone version in K8s environmentTomcat+my ...

catalogue 1, System introduction 1. Development environment 2. Technical selection 3. System functions 4. Database 2, System display 1. Log in to the system 2. User registration system 3. User - main interface 4. User - user orders 5. User - query order 6. User - change password 7. Administrator - main interface 8. Administrator - ...

[TOC] environment It's not easy to go back to the Java series! IDEA 2020.2 Maven 3.6x Window 10 PHP study (providing service environment in Windows (mysql5.7)) reference resources: https://mybatis.org/mybatis-3/zh/getting-started.html (official documents) Video: station B crazy God No one is a natural master. Only continuous inner scro ...

Indexes Data structure to help mysql obtain data efficiently Disadvantages: it reduces the efficiency of updating tables and increases disk overhead. B tree and B + tree The number of B's in the m-fork contains at most m-1 keys per node, while the number of B's + contains at most M keys The leaf node of the B + tree stores all key informati ...

preface This blog follows the content of the previous blog and supplements the DQL language. It mainly talks about the sorting query, common functions and grouping query in the DQL language. These three pieces of content mainly reflect the sorting and grouping query functions of MySQL. Here is the link to the blog that knows MySQL for the ...

MySQL permission connection 1, MySQL connection login 1. MySQL login mode under Linux 2. Password free login 2, Authority management 1. Concept of user + IP 2. User authority management 3. Basic operation 4. Revoke authority 3, Authorization practice 1. General authorization 2. Access method of authorization table and column 4, MySQL simula ...

catalogue 1. Installation and deployment of MySQL database 2. Web database mysql 3.MySQL asynchronous replication   1.mysql master-slave replication Configure slave database Master slave replication process   2.GTID copy 3.mysql delayed synchronization 4. mysql parallel replication 4. Semi synchronous replication of MySQL da ...

preface Tip: Here you can add the general contents to be recorded in this article: For example, with the continuous development of artificial intelligence, machine learning technology is becoming more and more important. Many people have started learning machine learning. This paper introduces the basic content of machine learning. Ti ...

1, Index overview 1. Introduction An index is a structure that sorts the values of one or more columns in a database table. Using an index can quickly access specific information in a database table. For example, index: if a certain page in the database is regarded as a book, the index is like a book directory. You can quickly find the locat ...