• If someone asks you about the principle of database, ask him to read this article (Reprint)


    When it comes to relational databases, I can’t help thinking that something has been ignored. Relational databases are ubiquitous and can range from small, practical SQLite to powerful Teradata. But few articles explain how databases work. You can Google / Baidu “relational database principle” to see how rare the results are 】And the articles we […]

  • Ten years of data analysis experience, summed up the best use of these three types of tools


    When it comes to data analysis tools, I believe you are familiar with them, but many people have a doubt? With so many data analysis tools, what’s the difference between them? Which is better? Which is stronger? Which should I learn? Although this question is a bit conventional, but it is very important, I have […]

  • Djongo: Django and mongodb connectors


    Mongodb is used as the back-end database in Django project, and the ORM framework of Django is not changed. Realize the addition and modification of files in mongodb database by Django user management program. usage 1.pip install djongo 2. Add the following code to setting.py under Django project: DATABASES ={ ‘default’:{ ‘ENGINE:’djongo’, ‘NAME’:’your-db-name’, } } […]

  • MySQL left join avoid pit Guide


    phenomenon left joinIn our usemysqlThe process of query is very common, such as how many comments a blog article has, how many comments a commodity has in the mall, how many likes a comment has, and so on. But because of the rightjoin、on、whereUnfamiliar keywords sometimes lead to inconsistent query results with expectations, so today I’ll […]

  • An understanding of MySQL transaction isolation


    Preface Let’s first introduce the concept of transactionTransactionIt is a logical unit of database management, which consists of an effective sequence of database operations. Acid characteristics of things Atomicity: the transaction is executed as a whole, either all successfully or all failed Consistency: refers to the consistency in logic, that is, all operations are in […]

  • Spring boot plus v1.2.3 release, CentOS quick install environment / build / deploy / start project


    Spring boot plus v1.2.3 release, CentOS quick install environment / build / deploy / start project [V1.2.3-RELEASE] 2019.09.09 Spring boot plus v1.2.3 release, CentOS quick install environment / build / deploy / start project ⭐️ New Features Project running environment installation script CentOS quick build / deploy / launch project script ⚡️ Optimization optimizationmaven-assembly-pluginProject packaging […]

  • Using Django to manage the existing database


    In most projects, there are always some almost invariable CRUD operations. It is boring to write these codes, but it is also one of the essential functions of the whole system. We also faced similar problems in the previous project. Although a relatively complete management background has been realized and code reuse has been achieved […]

  • A simple demo of express + jade + MySQL + bootstrap + nodejs


    Nodejs is developing rapidly. At present, the hottest nodejs construction framework is not express. It can be proved that there are 32K stars on GitHub. Next, take nodejs as the center to build a simple demo that includes both front and back ends. No matter what project is developed, it will be easy to understand […]

  • MySQL time type and mode


    When I was inMySQLAn error is reported when trying to insert a data with a time stamp in the database: mysql> insert into alarm_service values (6, ‘1970-01-01 08:00:00’); ERROR 1292 (22007): Incorrect datetime value: ‘1970-01-01 08:00:00’ for column ‘time’ at row 1 #View table structure mysql> show create table alarm_service; +—————+————————————————————————————————————————————————————————————————————————————–+ | Table | Create […]

  • Is Django suitable for systems with large number of users?


    There are several points to answer: 1. First of all, this is actually a technical selection problem. When selecting technology, we should not only consider performance, but also give priority to business type and team level. In addition, the framework is only one of them, and there are supporting facilities. If it’s data-driven, especially if […]

  • Pessimistic lock and optimistic lock in database


    Now let’s talk about pessimistic locks and optimistic locks in the database. Pessimistic lock Pessimistic lock, as its name suggests, is more pessimistic. It is always believed that every time the data is modified, other threads will also modify the data at the same time. So the pessimistic way to lock is to lock after […]

  • Summary of MySQL installation


    I. MySQL installation Recently, I received a requirement that I need to write SQL statements to check the database, start from scratch, and start from MySQL installation. There’s nothing to say about the installation. You can download the appropriate version on the official website and install it step by step. I use the Mac to […]