Programmer Think

1. Introduction MySQL still maintained a strong database popularity growth trend in 2016. More and more customers build their applications on MySQL database, and even migrate from Oracle to MySQL. However, some customers encounter some problems in the process of using MySQL database, such as slow response time, full CPU, etc. Alibaba cloud R ...

Learn Mysql from scratch - character set and encoding (Part 2)introductionThis series of articles is based on the personal notes summary column of "how MySQL works: understanding MySQL from the root". It is highly recommended that you read this book carefully. It is also one of the few good books that tell the principle of MySQL. Well ...

Author: Hu ChengqingMember of aikesheng DBA team, good at fault analysis and performance optimization, personal blog: https://www.jianshu.com/u/a95... , welcome to the discussion.Source: original contribution*It is produced by aikesheng open source community. The original content cannot be used without authorization. For reprint, please contact ...

https://www.zabbix.com/documentation/current/manual/concepts/server server installation #Download configuration using yum # rpm -Uvh https://repo.zabbix.com/zabbix/5.0/rhel/7/x86_64/zabbix-release-5.0-1.el7.noarch.rpm # yum clean all # vim /etc/yum.repos.d/zabbix.repo [zabbix-frontend] ... enabled=1 ... #zabbix package d ...

1 Introduction What is Cache? There is temporary data in memory.Put the data frequently queried by users in the cache (memory), and users do not need to query from the disk (relational database data file) but from the cache to query the data, so as to improve the query efficiency and solve the performance problem of high concurrency sy ...

1. Constraints 1.1 PrimaryKey(PK): primary key Features: unique + non empty, a table can only have one primary key constraint It is usually a numeric column Better be meaningless 1.2 NOT NULL Features: cannot be empty. We recommend that the business key column (index column) be set as non empty as possible 1.3 UNIQUE constraint Features: ...

background As required by the company, it is now necessary to make statistics on the data of the questionnaire filled in by the user. The final presentation style is EXCEL, and the content is the options of each question filled in by the user, that is, the following table style: User ID numberQuestion 1Question 2Question 3...Question 22110000 ...

1, Case analysis Table structure of query Get data from multiple tables: -- Wrong query method: query employees Tabular id and departments Name of the table SELECT employee_id, department_name FROM employees, departments; # 2889 records, there can't be so many, it's wrong SELECT * FROM employees; #107 SELECT 2889/107 FROM DUAL; # ...

Then, in the previous period, the data was queried without writing an sql in the previous period. What if you want to save or update the data? Can you write your own sql? Save data @GetMapping("save")//Save data public void save(@RequestBody User user){ userJpa.save(user); } Add the above method in UserController. Using @RequestBody ...

preface    in recent days, I have taken time to add several new functions to the code generator (it is expected to be released tonight). At present, it supports postgresql database, HikariCP connection pool and swagger2 (there is a link to the generator at the end of the article. Friends who like it can download it for free forever. ...