For the convenience of JavaRush students, we decided to collect lectures and articles about the most important topics in programming. The eleventh selection is about databases and the SQL query language. In the mini-guide, we briefly outline the essence of the articles, and if you follow the link, you can learn more about the topic of interest. Add the collection to your bookmarks and return to it when needed. ![Bookmark: everything you need to know about databases and the SQL language - lectures, articles and videos - 1]()
Articles and lectures
This article opens a short series devoted to the basics of interacting with databases in Java and an introduction to the SQL language. Many programs are busy processing and modifying information and keeping it up to date. Since data is a very important part of program logic, separate storage is often allocated for it. Data is accessed and modified using a special query language - SQL (Structured Query Language). This article will be useful if you are just getting started with databases.
This second part of the text is about an introduction to SQL. Here the author continues to analyze the principles of operation of databases and SQL using the example of creating a stock exchange emulator.
A large series of articles about creating your own portfolio project. Naturally, he understands the various technologies with which the programmer interacts. Including databases and SQL language. The result of the articles is writing a telegram bot.
In the second part, the author focused on practice: he provides guidance on installing MySQL, writing the first lines in this language, and creating your first database. At the end you will have homework.
In the third part of the database analysis, the author talks about the SELECT operator, WHERE, ORDER BY, GROUP BY parameters. At the end, as before, homework awaits.
As the name implies, the entire fourth part is devoted to the analysis of homework. We recommend reading it - the task is interesting, and you might want to do it.
In the fifth part, the author talks about types of connections and joins: explains what one-to-many, one-to-one, many-to-many and other concepts are.
This final article on databases covers the final homework assignment. It is interesting because it is intended for interviews at the Middle level. That is, after this task you can already go for an interview, and you will successfully pass at least part of what relates to relational databases.
There are a huge number of book options suitable for an initial dive into SQL, but the author of this post settled on “SQL. Collection of recipes” by Anthony Molinaro. The peculiarity of the book is that in addition to studying SQL at a basic level, you will become familiar with several databases at once and see how the queries for them differ and what are the features of a particular database.
We offer you an adaptation of Lukas Eder's article, designed for those who have a general understanding of databases and SQL, as well as some practical experience with DBMS. It describes five simple optimizations that can be implemented based only on metadata (that is, constraints) and the query itself.
In Part 2, you'll learn about eliminating "meaningless" predicates and projections in EXISTS subqueries.
The third part of the article deals with the merging of predicates and provably empty sets.
The fourth part describes the limitations of CHECK and unnecessary reflexive joins.
The final part of the article talks about such optimization as pushing objects.
If you've been following trends in backend development and Big Data, you've probably already noticed the buzz around NoSQL databases in recent years. This article talks about why they were created in the first place, what problems they solve, and why so many different databases are suddenly needed.
Probably the most important thing you can learn to write effective SQL queries is indexing. However, in second place, very close behind, is the knowledge that many SQL clients require the database to do a lot of "unnecessary but necessary work." What this is will be discussed in this article.
A series of articles on how to create a database and connect it to a Rest application.
In the last part, we learned how to install a PostgresSQL database on a computer, create a database in pgAdmin, and also create and delete tables in it manually and programmatically. In this part, the author invites readers to rewrite the program so that it learns to work with this database and tables.
In this article, the author talks about one of the key topics in technical interviews - databases. It looks at the most common questions and tries to answer them without diving deep into the material.
Hibernate is a framework that was invented to make life easier for programmers. It eliminates duplicate code and hides the code needed to manage resources, reducing errors. By working with Hibernate, the developer can focus on the business logic of the application. Essentially, Hibernate acts as an adapter when connecting an application to a database. Read the article about the demand for this framework and what projects it will be needed for.
Videos
Java development is inseparably linked with the backend. And the backend is with databases. If you don't want to face problems in a technical interview where you might be asked anything about databases, watch this Podlodka Backend Crew database test interview stream. You will learn the theory of working with databases and specific technical solutions for each of the most common databases: SQL, NoSQL, NewSQL.
To connect an IntelliJ IDEA project to the Amazon Web Services cloud using the MongoDB DBMS, IDE skills are not enough. In addition to the development environment, you will also have to learn how to operate the synchronous or asynchronous MongoDB driver, the MongoClient client, and learn about working with collections. This video walks you through all the necessary steps to connect a database to a Java project. In the description below the video there is a link to the project code in IntelliJ IDEA.
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