Young-han Kim's Practical Database - Basic Course

"A query that ran perfectly during development suddenly slows down as data accumulates." At such times, the mark of a truly skilled developer is identifying the root cause based on solid evidence rather than guesswork, and optimizing a 30-second query down to 0.1 seconds. Master the core principles of database performance—from execution plans, indexes, and optimizers to joins and sorting—using millions of rows of real-world data. Elevate your skills and become a top-tier developer capable of independently analyzing and resolving slow queries in production environments.

Spring beginners can grasp core principles and solidify basics via examples.

Beginners to Spring can quickly learn the entire Spring web application development process by creating examples.

This is a Java course for those who are new to programming. You can easily learn Java by following along with the code.

Learn practical core Java object-oriented concepts easily via example code.

Not only developers, but also planners and data analysts learn databases step-by-step, starting from the basics of SQL.

This book provides an in-depth study of various intermediate-level Java features necessary for practical work, using example code.

Learn Java generics and collection frameworks in depth with a focus on practical applications. Also learn the basics of data structures.

With a practical example, we will design and develop a web application using Spring Boot and JPA. Through this process, you will understand how to use Spring Boot and JPA in practice.

For those who are new to JPA or who use JPA in practice but lack basic theory, By learning the basic theory of JPA solidly, even beginners can confidently use JPA in practice.

Learn the core HTTP features essential for practical use and how to design proper HTTP APIs.

You can understand and master all the web technologies required to develop web applications from the basics. You can understand the core principles and structure of Spring MVC and grow into a more in-depth backend developer.

Learn the essential modern Java technologies of Lambda, Stream, and functional programming with Java, from the basics to the practical level, in depth.

Learn I/O, networking, reflection, and annotations in depth, from the basics to the practical level. Build a web application server (WAS) directly in Java.

This course provides an in-depth study of multithreading and concurrency, from basic principles to practical applications.

You can utilize and implement the database data access technologies required for backend development. You will understand the principles and structure of Spring DB access technologies and grow into a more in-depth backend developer.

You will systematically learn database design through three stages—conceptual, logical, and physical—and strengthen your skills through a practical shopping mall project. Gain real-world know-how through modern design techniques and the latest trends.

Develop APIs using Spring Boot and JPA. And learn how to optimize JPA's extreme performance.

Solve the challenges you inevitably face in real-world design—such as common codes, category hierarchies, history tracking, soft deletes, statistics, dynamic design, and JSON utilization—with 9 core patterns. This is not just simple theory; it contains practical know-how and selection criteria for various scenarios, proven across numerous projects. Now, become a true design expert who can confidently handle any requirement that comes your way.

You can understand all the web technologies required for web application development from the basics and complete your learning. In MVC Part 2, you can learn all the practical application techniques needed for real-world web development, building upon the core principles and structures from MVC Part 1.

Solve the challenges you inevitably face in real-world design—such as common codes, category hierarchies, history tracking, soft deletes, statistics, dynamic design, and JSON utilization—with 9 core patterns. This is not just simple theory; it contains practical know-how and selection criteria for various scenarios, proven across numerous projects. Now, become a true design expert who can confidently handle any requirement that comes your way.

Starting from installing MariaDB and understanding its structure, you will learn step-by-step from writing SQL queries and utilizing functions to joins and subqueries. You will master core practical features such as table design, performance management, backup, and recovery through hands-on practice, completing the practical skills necessary for database development and operation.

This course is a master class that systematically covers the fundamental principles and practical applications of MongoDB. Starting with core MongoDB concepts, you will systematically learn essential topics for practical work, such as database design, CRUD operations, indexing, aggregation pipelines, performance optimization, transactions, and security. It explains topics step-by-step so even beginners can understand, and you can deeply learn the working principles of MongoDB through exercises and examples. This is the best introductory and practical course for developers who want to build strong MongoDB skills for practical work.

Not only developers, but also planners and data analysts learn databases step-by-step, starting from the basics of SQL.

A beginner's guide to SQL coding! We'll teach you the secrets of writing, interpreting, and validating SQL.

This course goes beyond simple CRUD-level database usage to help you acquire PostgreSQL skills necessary for the AI era from a practical perspective. Based on AI development experience in Silicon Valley, you will learn step-by-step how to design and utilize JSON, indexes, transactions, and even pgvector in real-world services, while mastering methods to solve complex data structures and performance issues.

This course provides a step-by-step learning path, ranging from the fundamental usage of MySQL to advanced techniques required in real-world production environments. It covers a wide range of topics, including data modeling techniques based on various case studies and practical data, evaluating the effectiveness of Foreign Key designs, analyzing Google Calendar schema DDL, and modern DDL design principles. Through this course, you will gain an in-depth understanding of how to utilize MySQL as a core system component rather than just a simple database.

Learn about Race Condition, a representative concurrency problem. Practice by comparing single server environments and distributed environments that cause concurrency issues. Understand transaction boundaries and isolation levels. Learn the differences between optimistic locking, pessimistic locking, and distributed locking.

Learn intermediate to advanced SQL and solve 101 real-world data analysis problems together to build solid SQL data analysis skills.

Learn how to analyze 5 million Korean apartment transaction data using PostgreSQL. Covers the process of data cleaning, transformation, and deriving meaningful insights through various SQL queries.

A guide to the exam for nationally recognized SQL qualifications! Establish a comprehensive knowledge system related to SQL.

Channel Talk interviewers will directly analyze the difference between failing and passing answers to the same questions, and help you prepare for actual follow-up questions.

"SQLD is an exam where past questions are not officially released." Preparing for the upcoming 60th exam (2026.3.7)— Practical study material featuring 50 vividly reconstructed questions by subject and chapter, based on the latest 59th exam!

SQLD Yellow Book 176 Problem-Solving Course for those who studied but can't solve problems. After completion, you'll go beyond passing to become an expert. SQLD All-in-One Pass!

Does game backend development feel daunting and vague? With know-how gained from firsthand experience with numerous projects, I will show you how to perfectly integrate complex Firebase features into actual games. We will connect Firebase to a Unity 6 Watermelon Game to implement online features such as login, cloud database (Firestore) save/load, rankings, bulletin boards, and mailboxes. This is a practical course that also covers security rules, Remote Config operations, and code design based on a layered architecture (UI, logic, and data access).

This is a course for learning MS-SQL through baseball and corporate databases.

This is a course on creating practical Unity games with databases. It covers topics that are usually difficult to encounter, explained through lectures.

SQLD, where should I start? For those of you feeling completely overwhelmed, this is the lecture for you. You will meet a transformed version of yourself after completing the course. SQLD All-in-One Pass!

Learn the SAGA transaction management technique for maintaining data consistency in distributed environments through a hands-on approach. You will configure three microservices using Spring Boot and Docker, and implement both Orchestration and Choreography patterns using Kafka and MySQL. Through this course, you will master core concepts applicable to real-world scenarios, including the operational principles of distributed transactions, designing compensating transactions, and handling fault recovery.

Knowledge Graph-based RAG System Implemented with Neo4J: Next-Generation Search Technology Utilizing Data Relationships Beyond Simple Vector Search Maximizing RAG Performance with the Power of Graph Databases!