The book "Structured SQL query language to databases in multi-user systems", written by a team of authors, is a unique and in-depth look at one of the most important tools in the world of information technology - the SQL language .. This edition will be especially useful for both beginners and experienced professionals seeking to improve their database skills. SQL, or Structured Query Language, is a language that allows you to interact with relational databases. In the rapidly developing world of technology, where data is becoming the new gold, the ability to effectively use SQL becomes not just an advantage, but a necessity. This book offers readers not only theoretical foundations, but also practical examples that will help them better understand how to apply SQL in real-world projects. One of the key topics addressed in the book is working with multi-user systems. In an environment where tens and hundreds of users can work at the same time, it is important not only to correctly form requests, but also to take into account the performance and security aspects. The authors consider in detail how to optimize queries to avoid bottlenecks and provide quick access to data. This makes the book especially relevant for developers, system administrators, and data analysts who work in high-load environments. The book also raises important issues related to transaction management and data integrity. In multi-user systems, where data can be changed simultaneously by multiple users, it is necessary to understand how to avoid conflicts and errors. The authors share useful tips and techniques that will help readers cope with such challenges. The style of presentation in the book is characterized by accessibility and clarity .. The authors use many examples and illustrations, which makes the material more understandable and easy to perceive. Readers will be able not only to get acquainted with the theory, but also to immediately apply the knowledge gained in practice. This is especially important for those who are learning on their own or want to quickly learn new skills. The book will be of interest to a wide range of readers: from computer science students to professionals working in the field of software development and data management. If you want to deepen your knowledge in the field of databases, improve your SQL skills or just look for a useful resource for self-education, this publication will be an excellent choice. In addition, the “Structured SQL query language to databases in multi-user systems” can be an excellent addition to the library of any IT specialist. Combined with other popular programming books and databases, such as SQL for Beginners or Designing Relational Databases, this publication will help create a solid foundation for further study. In conclusion, this book is not just a textbook, but a valuable resource that will help you become a more confident and competent SQL user. It is noteworthy for its practical approach, relevance of themes and accessible style of presentation. If you want to master the SQL query language and learn how to work effectively with databases in multi-user systems, this publication will be your reliable assistant along the way.