Java ORM Standard JPA Programming - Basics
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.
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Hello. I am Kim Young-han.
Finally, the full backend developer roadmap that I first set as a goal 7 years ago is now complete.
Following the completion of the entire roadmap and in response to many requests to reopen the Backend Master Pass, I am introducing Young-han Kim's Backend Master Pass for a limited time.
Link: https://inf.run/uixFt
With the release today of the final course, "Kim Young-han's Practical Database - Performance Optimization," I have now completed the entire roadmap, spanning from Practical Java to Spring, JPA, database design, and performance optimization.
It took seven years to reach this point after starting the very first lecture.
I would like to express my sincere gratitude to all of you who have been with me for such a long time.
A 7-Year Epic Journey, and Its Completion
When I first started the lecture, I had one goal.
Reflecting on the countless junior, mid-level, and senior developers I've met in the field, my goal was to consolidate all the practical skills necessary for developers to truly grow into a single, comprehensive roadmap.
Rather than merely explaining a single specific technology,
Fundamentals of Java and Object-Oriented Programming
Core Principles of Spring
Practical Development Using Spring Boot and JPA
Database Design
Large-Scale Data and Performance Optimization
I wanted to comprehensively cover all the topics that a backend developer inevitably encounters as they grow.
My goal was to properly put together the entire journey needed to grow from a newcomer to a junior, and then to a senior.
And now, seven years later, the entire roadmap I originally envisioned has finally been completed, culminating with the database performance optimization lecture.
Looking back, it has been a truly long journey.
While creating the lectures, I reshot the sessions countless times and constantly sought ways to deliver better explanations. I also meticulously deliberated and verified every detail to ensure that only the most essential content for real-world practice was included.
Honestly, maintaining something like this for so long is no easy feat. I, too, have fallen into slumps countless times and endured moments of sheer exhaustion and hardship. There were many days when I would come home after a hectic day at the office, completely drained, and record lectures late into the night.
Looking back, what got me back on my feet during those moments were each and every course review you left. All those messages where you took my lectures, cheered me on, and shared your stories of growth—like studying hard and landing a job at your dream company—were a tremendous source of strength for me. Those small words of encouragement that piled up over time were ultimately the greatest reason I was able to see this long journey through to the very end. Every time I read a review, and every time someone recognized me in passing and greeted me warmly, it gave me the strength to realize that the work I do is truly making a difference in someone's life.
Looking back, this entire process was never something I built alone. It was a time we created together, a journey we completed together.
I sincerely thank you.
Limited-Time Launch of the Backend Master Pass
In response to the completion of the entire roadmap and numerous requests to reopen the Backend Master Pass, we are pleased to introduce Kim Young-han's Backend Master Pass for a limited time only.
Link: https://inf.run/uixFt
This Master Pass is a comprehensive roadmap that covers everything from the fundamentals to real-world practice for backend developers, all the way to the system design and performance optimization that senior developers need to tackle.
Pass Product Configuration — Integrating 4 Core Roadmaps
The Backend Master Pass includes the following 4 complete roadmaps.
Kim Young-han's Practical Java Roadmap
Kim Young-han's Complete Spring Mastery Roadmap
Kim Young-han's Complete Mastery Roadmap for Spring Boot and JPA in Practice
Kim Young-han's Practical Database Roadmap
You can learn everything in one seamless learning path, starting from Java's basic syntax and object-oriented programming, and progressing to Spring, JPA, database design, and performance optimization.
This time around, the entire Backend Master roadmap has been completed with the official addition of the final piece of the puzzle: "Kim Young-han's Practical Database - Performance Optimization."
The Last Puzzle, Database Performance Optimization
As your service grows and data begins to accumulate, you will inevitably encounter database performance issues.
Queries that run smoothly during development can suddenly slow down in the production environment, and even a single simple query can sometimes become a bottleneck or cause an outage across the entire service.
What is needed at this point is not simply a quick fix of adding a few indexes.
You need to understand how the database stores and retrieves data, how to analyze execution plans, and why the optimizer chooses a specific index and join order.
This performance optimization lecture covers the following topics.
Analyzing Execution Plans Using EXPLAIN and EXPLAIN ANALYZE
B+Tree and the Internal Structure of Indexes
Clustered Index and Secondary Index
Principles of Composite Index Design
Diagnosing and Optimizing Using filesort
ICP, Covering Index, Skip Scan
Optimizer and Histogram
Join and Random Access Optimization
Sorting, Paging, and Grouping Performance Optimization
Large-Scale Statistics Processing Using Pre-Aggregated Tables
Now, you have completed the entire journey, moving beyond just building applications properly to directly analyzing and resolving the performance issues that arise as your service scales.
Why a Comprehensive Roadmap is Needed in the AI Era
As we enter an era where AI writes code, a developer's foundational skills are becoming more important than ever.
AI is not a tool that replaces a developer's capabilities, but rather one that amplifies them.
Developers with solid fundamentals can ask AI better questions and verify whether the results it generates are correct.
Conversely, without a solid foundation, even if the code appears to work on the surface, it is difficult to detect the following problems.
Code with broken object-oriented design
A structure difficult to maintain
Improper transaction handling
Inefficient data access
Queries that cause failures in production
A design that slows down as data grows
AI technologies and tools will continue to evolve, but the fundamentals remain unchanged: the ability to distinguish good code from bad, the principles of object-oriented programming, how HTTP and the web work, transactions, and database design and performance optimization.
Only when you truly understand can you ask the right questions, verify your work, and refine your approach to achieve better results.
This Backend Master Pass captures the very essence of what remains unchanged.
Continuous Course Renewal
The entire roadmap is complete, but lecture production is not yet finished.
Going forward, we plan to continuously update our existing courses to keep pace with technological advancements and real-world work environments.
As needed, we will carry out full and partial video renewals, as well as updates to the manuals and example projects.
Those who purchase the Master Pass will have continuous access to all updated content at no additional cost, even if the lectures are renewed or prices change in the future.
It is the very least courtesy and a promise to those who trusted me and chose me.
Lastly,
This pass is not merely a bundle of multiple courses.
This is the culmination of everything I have learned, the failures I have faced, and the challenges I have wrestled with over years of hands-on experience, all distilled into a single growth journey.
I will be your steadfast guide as you progress from a newcomer to a junior, and from a junior to a senior, until the day you become the kind of developer your colleagues truly want to work with.
Thank you.
Hello, everyone.
Young-han Kim's Practical Database Performance Optimization course has finally launched.
To celebrate the launch, we are offering a 30% discount on the Database Roadmap 🙂
Title: Kim Young-han's Practical Database - Performance Optimization, Complete Mastery of Execution Plans and Indexes
Number of lectures: 104
Course duration: 21 hours 10 minutes
Link: https://inf.run/Gcg6N
And to celebrate the completion of all lectures in the Backend Roadmap, including the Database Roadmap, we are introducing Kim Young-han's Backend Master Pass for a limited time only.
Master Pass Link: https://inf.run/uixFt
<Course Features>
The most important feature of this lecture is that we will load real-world data ranging from millions to tens of millions of records into the database and tune it step by step together. Through this, you will learn practical methods to optimize queries that previously took several seconds down to the extreme of 0.01 seconds.
<Course Content>
During development, queries that run smoothly can suddenly slow down as data accumulates.
A query that initially executes in just 0.1 seconds can suddenly take over 1 second or 10 seconds, and in severe cases, it may lead to a service outage.
In such situations, we find ourselves asking the following questions.
Where should we start looking for the cause of slow queries?
What do the numerous items in the execution plan mean?
I created an index, but why isn't it being used?
In what order should composite indexes be designed?
Does having more indexes improve performance?
Why does filesort occur, and how should it be eliminated?
Why do queries slow down as you paginate further back?
Who determines the join order, and how can it be optimized?
Why does the optimizer choose an execution plan different from our expectations?
Database performance issues cannot be solved simply by knowing SQL syntax well.
You need to understand how the database stores data, how it traverses indexes, and the criteria the optimizer uses to select an execution plan.
Rather than fixing slow queries by guesswork, this course covers how to identify the root cause and resolve it based on the execution plan and actual measurement results.
First, you will learn the internal architecture of MySQL and InnoDB and analyze how queries are actually executed using EXPLAIN and EXPLAIN ANALYZE.
After that, we will directly create and resolve performance issues using millions of rows of real-world data.
Optimizing Full Table Scans into Index Scans
Determining the Column Order of a Composite Index
Understanding B+Tree and Internal Index Operations
Analysis of Clustered and Secondary Indexes
Diagnosing the Cause of Using filesort and Early Termination
Performance Improvement Using ICP and Covering Indexes
Index Skip Scan, Index Merge, MRR Analysis
Leveraging the Optimizer and Histograms
Join Order and Random Access Optimization
Sorting, Paging, and Grouping Performance Optimization
Streaming Aggregation and Pre-aggregation Table Design
We don't just give you the conclusion and say, "Add an index here."
We examine step by step why that index is necessary, what happens inside the database, and how the execution plan and actual execution time differ.
Furthermore, it goes beyond merely optimizing a single query, delving deeply into the fundamental principles that empower you to continuously analyze and resolve new performance issues in real-world scenarios.
<What You Will Gain from This Course>
1. Ability to read execution plans
Understand the key metrics of EXPLAIN and EXPLAIN ANALYZE, and identify the root causes of slow queries within the execution plan.
2. The ability to design indexes directly
Beyond simply adding an index to a single column, you will be able to design composite indexes tailored to data distribution and query conditions.
3. Understanding Database Internals
You will understand the core principles of index internals, including B+Trees, clustered indexes, secondary indexes, and random access.
4. Real-World Performance Optimization Experience
You will analyze slow queries firsthand using millions of records and experience the process of optimizing them to achieve performance improvements of tens to hundreds of times.
5. Criteria for Resolving Issues in the Production Environment
You can choose the optimal approach for any given situation by considering not only the benefits of indexes, but also write performance, storage space, and operational costs.
<Full Curriculum>
Course Introduction and Materials
Lab Environment Setup
Database Performance and MySQL Architecture
Execution Plan 1 - Mastering EXPLAIN
Execution Plan 2 - Mastering ANALYZE
Practical Tuning 1 - Full Table Scan Diagnosis and Composite Index Basics
Index Internal Structure 1 - B+Tree
Index Internal Structure 2 - Clustered, Secondary Indexes
Practical Tuning 2 - Diagnosing Using filesort and Early Termination
Advanced Indexing 1 - ICP, Covering, Skip Scan
Advanced Indexes 2 - Merge, MRR, New Features, Hints, Operations
Optimizer and Histogram
Join Optimization
Practical Tuning 3 - Diagnosing Join Random Access and Covering Indexes
Sorting, Paging, and Grouping Optimization
Practical Tuning 4 - Streaming Aggregation and Pre-aggregated Tables
Next,
Database performance optimization is not simply a matter of memorizing a few SQL tuning techniques.
It is a process of understanding the data retrieval path, identifying bottlenecks based on execution plans, and determining the most appropriate solution among various options.
Through this course, I hope you grow into a developer who can accurately analyze the root cause and resolve issues independently, rather than blindly adding indexes when encountering slow queries.
In this lecture, I have distilled the experience I've gained from resolving countless performance issues in real-world settings, along with the insights from years of careful consideration.
I hope this has been helpful for your growth.
Thank you.
Hello. I'm Young-han Kim.
We are introducing the Younghan Kim's Backend Master Pass, which many of you have requested for a long time, for a limited period.
Link: https://inf.run/LR9Sp
A 7-year journey, and its completion
It has already been 7 years since I started my first lecture. During that time, I have created a total of 26 lectures and received overwhelming support with a cumulative total of 590,000 students.
When I first started teaching, I made a promise to myself. Thinking of the countless new, junior, and senior developers I met in the field, I vowed to create "real-world development courses that truly enable growth." My goal was to deliver every practical skill needed to grow from a newcomer to a junior, and from a junior to a senior—and it has finally been completed after 7 years.
Pass Product Composition — Integration of 4 Core Roadmaps
This Master Pass is a 'lifelong roadmap' that accompanies a developer's entire career cycle, from the basics of their junior days to the performance optimization challenges they must face as a senior.
Young-han Kim's Practical Java Roadmap
Young-han Kim's Spring Complete Mastery Roadmap
Young-han Kim's Roadmap for Mastering Spring Boot and JPA in Practice
Young-han Kim's Practical Database Roadmap
Includes new lecture to be released in July
In addition to this, the 「Young-han Kim's Practical Database - Performance Optimization」 course, scheduled for release in July, will be provided. (Expected price: 154,000 KRW)
This is the course I am putting the most effort into creating. This is because 80% of practical system failures stem from database performance issues. As a service grows and begins to handle large-scale traffic, no matter how cleanly you write your backend application code, the final bottleneck will eventually explode at the database level.
After mastering this course, you will possess the 'true senior's' perspective to accurately pinpoint bottlenecks without panicking, even in the face of failures or slow queries.
A reward for existing students
I have prepared some benefits for those who have trusted and followed me for a long time.
- Existing Course Purchasers: A higher discount rate will be applied to the remaining courses based on the number of courses (amount) already owned.
- Purchasers of all courses (Super Fans): Master Pass provided as a gift (free)
As a special thank you to my true fans who have trusted and followed all of my lectures so far, I am giving the 'Pass Product' and the 'Practical Database Performance Optimization' lecture, which will be released in July, as a gift. (Please make sure to select the 0 won purchase for the Pass Product!)
The AI Era: Why Fundamentals Matter
An era where AI writes code for us. Has the gap between skilled and unskilled developers narrowed? In the field, the opposite result is actually occurring.
AI is not a tool to replace a developer's ability, but a tool to amplify it.
Skilled developers can ask AI the right questions and determine whether the code generated by AI is high-quality or dangerous. They can quickly identify if the design is flawed, if there are hidden performance issues, or if it could lead to failures in a production environment.
Conversely, if you lack the fundamentals, it is difficult to verify the results generated by AI. Even if it appears to work on the surface, the design might be flawed, database performance issues could be hidden, or problems could erupt in the production environment.
AI technology will continue to change rapidly. However, there are things that do not change.
The basic principles of object-oriented programming
The eye to distinguish between good code and bad code
The operating principles of HTTP and the web
Transactions and Data Access Technologies
Database design and performance optimization
These fundamentals become even more important in the AI era. This is because you need to know to ask questions, you need to know to verify, and you need to know to make improvements.
This Backend Master Pass contains those very unchanging essentials.
Continuous lecture renewals, at no additional cost
Going forward, existing lectures will also be continuously renewed. Depending on the need, we will proceed with full video renewals, partial video renewals, manual version updates, and more.
Those who purchase the Master Pass now will receive free updates without any additional cost, even if the price of the renewed lectures increases later. This is my minimum courtesy and promise to those who have trusted and chosen me. I plan to begin full-scale renewal work after the release of the Practical Database Performance Optimization lecture.
Lastly
This pass is not simply a product for selling knowledge. It is the culmination of seven years of effort, created to pass on to you everything I have learned, experienced, and fiercely contemplated in the field for over a decade.
Until the day you grow from a newcomer to a junior, from a junior to a senior, and finally become a developer whom your colleagues sincerely want to work with—I will be by your side as a reliable guide.
Thank you.
･
Edited
Hello everyone
The Database Design Part 1 course has finally opened.To celebrate the opening, I'm offering 30% off all my courses 🙂
Title: Kim Young-han's Practical Database Design Part 1 – Complete Mastery of Modern Data Modeling
Number of lectures: 83
Lecture Duration: 16 hours 11 minutes
Lecture PDF materials: approximately 400 pages
Link: https://inf.run/SEdxb
[Course Introduction]
Databases are the foundation of all applications.
However, if not designed properly, projects quickly hit their limits, and maintenance becomes hell.This course doesn't simply teach you how to create tables, but systematically shows you modern database design methods that work in real-world practice. And I've packed this course with the results of my extensive hands-on experience and long deliberation.
[Key Lecture Points]
Conceptual → Logical → Physical Modeling
Master DB design completely with a 3-step approach.Design know-how you can use immediately in practice
We don't just stay in theory, but use a shopping mall project as an example.Avoiding the Pitfalls of Poor Design
Through hands-on practice, you'll understand why ERDs are important, why normalization is necessary, and when denormalization should be applied.The Essence of Key and Relationship Design
We cover natural keys vs surrogate keys, one-to-one, one-to-many, and many-to-many relationships, and identifying vs non-identifying relationships in depth.Reflecting the Latest DB Design Trends
We don't stay stuck in textbooks from decades ago, but present modern data modeling methodologies.[What You'll Learn]
Requirements Analysis and Core Entity Extraction
ERD Creation and Terminology Dictionary Management
Normalization (1NF ~ BCNF) and Its Limitations
Index and Performance-Considered Physical Modeling
Shopping Mall Project Complete DB Design Practice
[Target Audience]
Developer: Someone who wants to design a proper database before writing code
Planner/Analyst: Those who want to fundamentally understand data flow and structure
Job seekers: Those who want to demonstrate differentiated DB design capabilities in interviews
Junior Developer: Those who want to learn design principles that can be applied immediately in practice
Senior Developer/Lead: Those who want to improve the quality of their team's database design
[Complete Course Curriculum]
1. Course Introduction and Class Materials
* 1-A. Windows - MySQL Installation Guide
* 1-B. macOS - Installation Guide
2. The Importance of Design
* The First Step in Database Design
* The Disaster Caused by Poor Design
* 3 Stages of Design - Conceptual, Logical, Physical
* Summary
3. Conceptual Modeling
* Requirements analysis and identification of key elements
* What is an entity?
* Entity Classification 1
* Entity Classification 2
* Properties and Identifiers
* Cardinality and Participation
* Complete the ERD
* Related Entity - Resolving Many-to-Many Relationships
* Glossary
* Summary
4. Conceptual Modeling - Practice
* Practical Requirements Analysis
* Practical Conceptual Modeling - Getting Started
* Practical Conceptual Modeling - ERD Creation
* Practical Conceptual Modeling - Glossary Creation
* Summary
5. Logical Modeling 1 - Keys
* Various types of keys
* Natural Key vs Surrogate Key1 - Natural Key
* Natural Key vs Surrogate Key2 - Surrogate Key
* Natural Key vs Surrogate Key3 - Performance Trade-offs
* Natural Key vs Surrogate Key4 - Modern Design
* Composite key design
* Many-to-Many Relationships and Composite Keys
* Summary
6. Logical Modeling 2 - Participation and One-to-Many Relationships
* Logical Modeling - Relationships
* Participation
* One-to-Many (1:N) Many-to-One (N:1) Relationships - Foreign Key Position 1
* One-to-Many (1:N) Many-to-One (N:1) Relationships - Foreign Key Position 2
* One-to-Many (1:N) Many-to-One (N:1) Relationships - Joins and Data Inflation
* Summary
7. Logical Modeling 3 - One-to-One, Many-to-Many Relationships
* One-to-one (1:1) relationship - Start
* One-to-one (1:1) relationship - Foreign key location
* One-to-One (1:1) Relationship - [Practice] Flexibility of Relationship Extension
* One-to-one (1:1) relationship - FK in the main table
* Many-to-Many (M:N) Relationship - Limitations of the Relational Model
* Many-to-Many (M:N) Relationship - Junction Table
* Many-to-Many (M:N) Relationship - Attributes
* Many-to-Many (M:N) Relationship - Conceptual and Logical Modeling
* Summary
8. Logical Modeling 4 - Identifying Relationships, Non-Identifying Relationships
* Identifying Relationship vs Non-Identifying Relationship - Concepts
* Identifying Relationship vs Non-Identifying Relationship - One-to-Many (1:N)
* Problems with Identifying Relationships
* Identifying Relationship vs Non-Identifying Relationship - SQL Queries, Performance
* Identifying Relationship vs Non-Identifying Relationship - One-to-One (1:1)
* Identifying Relationship vs Non-Identifying Relationship - Many-to-Many (M:N) 1
* Identifying Relationship vs Non-Identifying Relationship - Many-to-Many (M:N) 2
* Identifying Relationships vs Non-Identifying Relationships - Modern Design Trends
* Summary
9. Logical Modeling - Practice
* Practical Logical Modeling - Getting Started
* Practical Logical Modeling - ERD Creation
10. Normalization
* Normalization - Start
* First Normal Form
* Second Normal Form
* Third Normal Form
* BCNF Normal Form
* Practice and Normalization
* Summary
11. Physical Modeling
* Physical Modeling Overview
* Table and Column Conversion Rules 1 - Basic Rules
* Table and Column Conversion Rules 2 - Abbreviations and Singular/Plural
* Data Type 1 - Character, Number, PK Type
* Data Types 2 - Date and Time Types
* Denormalization
* Table Definition Document
* Summary
12. Physical Modeling - Practice
* Physical Modeling - Practice Start
* Index Design - Practice
* Denormalization - Practice
* Shopping Mall Table Definition Document
* Creating Shopping Mall DDL and DB
* Physical Model - Automatic ERD Generation
* Shopping mall feature check 1
* Shopping mall feature check 2
* Summary
Thank you.
Hello everyone
The Database Design Part 1 course is finally ready to open.The Design Part 1 to be released this time is scheduled to launch between September 16th and September 19th.
Database Roadmap - Course Release Schedule
Design Part 1 – Complete Mastery of Modern Data Modeling - Expected release in mid-September
Design Part 2 - Mastering Practical Design Patterns and Application Techniques - Scheduled for release at the end of 2025
Performance Optimization and Advanced Features - Scheduled for release in early 2026
Title: Kim Young-han's Practical Database Design Part 1 – Complete Mastery of Modern Data Modeling
Number of lectures: 83
Lecture Duration: 16 hours 11 minutes
Lecture PDF materials: approximately 400 pages
Course Introduction
Databases are the foundation of all applications.
However, if not designed properly, projects quickly hit their limits, and maintenance becomes hell.This course doesn't simply teach you how to create tables, but systematically shows you modern design methods that work in real-world practice. And I've packed this course with the results of my extensive hands-on experience and long deliberation.
Key Points of the Lecture
* Conceptual → Logical → Physical Modeling
Completely master DB design with a 3-step approach.
* Design know-how for immediate practical use
We don't just stay in theory, but use a shopping mall project as an example.
* Avoiding the Pitfalls of Poor Design
You'll realize through hands-on practice why ERD is important, why normalization is necessary, and when denormalization should be applied.
* The Essence of Key and Relationship Design
Natural Key vs Surrogate Key, One-to-One, One-to-Many, Many-to-Many relationships, and Identifying vs Non-Identifying relationships are covered in depth.
* Reflecting the Latest DB Design Trends
It presents modern data modeling methodologies without being stuck in textbooks from decades ago.
What You'll Learn
Requirements Analysis and Core Entity Derivation
ERD Creation and Terminology Dictionary Management
Normalization (1NF ~ BCNF) and Its Limitations
Index and Performance-Considered Physical Modeling
Shopping Mall Project Complete DB Design Practice
Target Audience
Developer: Someone who wants to design a proper database before writing code
Planner/Analyst: Those who want to fundamentally understand data flow and structure
Job seekers: Those who want to demonstrate differentiated DB design capabilities in interviews
Junior Developer: Those who want to learn design principles that can be applied immediately in practice
Senior Developer/Lead: Those who want to improve the quality of their team's database design
Complete Course Curriculum
1. Course Introduction and Class Materials
* 1-A. Windows - MySQL Installation Guide
* 1-B. macOS - Installation Guide
2. The Importance of Design
* First Steps in Database Design
* The disaster caused by poor design
* 3 Stages of Design - Conceptual, Logical, Physical
* Summary
3. Conceptual Modeling
* Requirements analysis and identification of key elements
* What is an entity?
* Entity Classification 1
* Entity Classification2
* Properties and Identifiers
* Cardinality and Participation
* Complete the ERD
* Related Entity - Resolving Many-to-Many Relationships
* Glossary
* Summary
4. Conceptual Modeling - Practice
* Practical Requirements Analysis
* Practical Conceptual Modeling - Getting Started
* Practical Conceptual Modeling - ERD Creation
* Practical Conceptual Modeling - Glossary Creation
* Summary
5. Logical Modeling 1 - Keys
* Various types of keys
* Natural Key vs Surrogate Key1 - Natural Key
* Natural Key vs Surrogate Key2 - Surrogate Key
* Natural Key vs Surrogate Key3 - Performance Trade-offs
* Natural Key vs Surrogate Key4 - Modern Design
* Composite key design
* Many-to-Many Relationships and Composite Keys
* Summary
6. Logical Modeling 2 - Participation and One-to-Many Relationships
* Logical Modeling - Relationships
* Participation
* One-to-Many (1:N) Many-to-One (N:1) Relationships - Foreign Key Position 1
* One-to-Many (1:N) Many-to-One (N:1) Relationships - Foreign Key Position 2
* One-to-Many (1:N) Many-to-One (N:1) Relationships - Joins and Data Multiplication
* Summary
7. Logical Modeling 3 - One-to-One, Many-to-Many Relationships
* One-to-one (1:1) relationship - Start
* One-to-one (1:1) relationship - Foreign key location
* One-to-One (1:1) Relationship - [Practice] Flexibility of Relationship Extension
* One-to-one (1:1) relationship - FK in the main table
* Many-to-Many (M:N) Relationship - Limitations of the Relational Model
* Many-to-Many (M:N) Relationship - Junction Table
* Many-to-Many (M:N) Relationship - Attributes
* Many-to-Many (M:N) Relationship - Conceptual and Logical Modeling
* Summary
8. Logical Modeling 4 - Identifying Relationships, Non-Identifying Relationships
* Identifying Relationship vs Non-Identifying Relationship - Concepts
* Identifying Relationship vs Non-Identifying Relationship - One-to-Many (1:N)
* Problems with Identifying Relationships
* Identifying Relationship vs Non-Identifying Relationship - SQL Queries, Performance
* Identifying Relationship vs Non-Identifying Relationship - One-to-One (1:1)
* Identifying Relationship vs Non-Identifying Relationship - Many-to-Many (M:N) 1
* Identifying Relationship vs Non-Identifying Relationship - Many-to-Many (M:N) 2
* Identifying Relationships vs Non-Identifying Relationships - Modern Design Trends
* Summary
9. Logical Modeling - Practice
* Practical Logical Modeling - Getting Started
* Practical Logical Modeling - ERD Creation
10. Normalization
* Normalization - Start
* First Normal Form
* Second Normal Form
* Third Normal Form
* BCNF Normal Form
* Practice and Normalization
* Summary
11. Physical Modeling
* Physical Modeling Overview
* Table and Column Conversion Rules 1 - Basic Rules
* Table and Column Conversion Rules 2 - Abbreviations and Singular/Plural
* Data Type 1 - Character, Number, PK Type
* Data Types 2 - Date and Time Types
* Denormalization
* Table Definition Document
* Summary
12. Physical Modeling - Practice
* Physical Modeling - Practice Start
* Index Design - Practice
* Denormalization - Practice
* Shopping Mall Table Definition Document
* Creating Shopping Mall DDL and Database
* Physical Model - Automatic ERD Generation
* Shopping mall feature check 1
* Shopping mall feature check 2
* Summary
Thank you.
･
Edited
Hello, everyone
The two introductory database fundamentals lectures have finally been launched: Now available.
We've decided to offer an introductory database course for free so that even beginners can learn databases without any pressure.
Kim Young-han's Practical Database Roadmap
Practical Database Introduction by Kim Young-han - Step-by-Step from SQL (Now Open)
Kim Young-han's Practical Database - Basic Course (Now Open)
Kim Young-han's Practical Database - Design Edition (Scheduled for Second Half of 2025)
Kim Young-han's Practical Database - Performance Optimization and Advanced Features (Scheduled for Second Half of 2025)
Target Audience
For your reference, this lecture has been designed to be accessible not only to developers but also to planners and data analysts.
Developer: Juniors, non-majors, and job seekers who want to build a solid foundation in database basics
Planner/Marketer: For those who need data-driven decision making
Data Analyst: Beginner who wants to build SQL skills
[Introducing the Roadmap from a Developer's Perspective]
If you're a developer, I recommend following the entire roadmap.
Many developers will relate to this: truly outstanding applications are ultimately built on well-designed databases. This is because there are problems that simply cannot be solved by application code alone—they lie within the database layer. This roadmap will fill in that other half of essential expertise, elevating you to the next level as a developer.
Beginner Course: First, build a foundation in databases and SQL basics through the 'Beginner Course'.
Basic Course: The basic course covers essential database fundamentals that every junior developer must know.
You'll gain the ability to solve any complex business requirement using SQL through joins, subqueries, unions, and case statements.
Build a solid foundation in essential SQL performance optimization for real-world applications by thoroughly understanding how indexes work.
You can develop stable applications that prevent data corruption by gaining a deep understanding of transactions and data integrity.
Design Course: The design course will elevate you to a higher level of developer. You'll learn how good database design determines an application's maintainability and scalability, and develop the ability to systematically model complex real-world requirements.
Performance Optimization and Advanced Features: Performance Optimization and Advanced Features is the final gateway to becoming a senior developer capable of handling large-scale traffic. You will master advanced techniques to identify database performance bottlenecks that no one else can solve and push your service to its limits.
By mastering this roadmap, you'll grow into a truly skilled developer who goes beyond simply implementing features—gaining deep understanding and optimization skills for both applications and databases, enabling you to find solutions to any challenging situation.
[Introduction to Roadmap from a Planning and Data Analyst Perspective]
If you're a planner or data analyst, I recommend taking the introductory course and continuing through the basic course.
Beginner Course: By learning the basics of SQL through the beginner course, you'll gain the speed and independence to instantly get the answers you need, no longer having to request data and wait.
Basic Course: In the Basic Course, we take one step further.
You'll enhance the depth of your analysis by using advanced SQL techniques like joins, subqueries, unions, and CASE statements to combine scattered data from multiple sources and reprocess it according to your own criteria.
With just these two courses, you'll become a key talent capable of improving services based on data, persuading organizations, and communicating effectively with development teams.
If you want to directly lead data-driven products, taking the advanced 'Design' course to deepen your understanding of data structures could be a great choice.
This roadmap's introductory and foundational sections will completely transform the way planners and analysts work with data.
Beginner Course - Section Contents
1. Course Introduction and Study Materials
2. Introduction to Databases
3. Starting the Database
4. SQL - Data Management
5. SQL - Retrieval and Sorting
6. SQL - Data Processing
7. SQL - Aggregation and Grouping
Beginner Course - Section Contents
1. Course Introduction and Study Materials
2. Join 1 - Inner Join
3. Join 2 - Outer Joins and Other Joins
4. Subquery
5. UNION
6. CASE Statement
7. 뷰(View)
8. Index1
9. Index 2
10. Data Integrity
11. Transaction
12. Stored Procedures, Functions, and Triggers
I've gathered your questions about roadmap progress and will answer them.
1. Basic Order of Progressing Through the Database Roadmap
- The basic order is Java -> Database -> Spring -> Spring Boot and JPA application.
2. Recommended Order for Progressing Through the Database Roadmap
The most effective learning sequence is to study the introductory and basic database courses right before Spring DB1 in the Spring roadmap.
Therefore, you will learn in the following order.
- ...
- Spring MVC2
- Database Fundamentals
- Database Fundamentals
- Spring DB Part 1
- Spring DB Part 2
- ...
We recommend completing at least the Database Fundamentals course before proceeding with the Spring Boot and JPA application roadmap.
I'll reorganize and let you know again about the database design section, performance optimization, and advanced features once they're released.
3. Will the course be based on MySQL or Oracle?
The hands-on exercises focus on MySQL, but the lecture content emphasizes universal knowledge that covers not only MySQL but relational database management systems (RDBMS) in general. Therefore, the goal is to achieve a broad understanding that isn't limited to any specific database.
To use an analogy, in this course we'll learn how to drive a car called MySQL. But rather than simply learning how to operate one specific car model, we'll focus on mastering the fundamental driving principles—like accelerators, brakes, and steering wheels—that apply to any car (RDBMS). These core concepts of RDBMS will be beneficial when working with other RDBMS systems as well.
Thank you.
･
Edited
hello everyone
Finally, the two lectures on database introduction and basics are ready to open.
Thank you for waiting and supporting us for a long time!
The release date is expected to be between July 30th and August 1st.
Kim Young-han's Practical Database Roadmap
Kim Young-han's Practical Database Introduction - Step by Step from SQL (Open)
Kim Young-han's Practical Database - Basics (Open)
Kim Young-han's Practical Database - Design (Scheduled for the second half of 2025)
Kim Young-han's Practical Database - Performance Optimization and Advanced Features (Scheduled for the second half of 2025)
Lecture target
Please note that this lecture has been designed to be easy to understand for not only developers but also planners and data analysts.
Developer : Juniors, non-majors, job seekers who want to build a solid foundation in database fundamentals
Planners/Marketers : Those who need data-driven decision making
Data Analyst : Beginners who want to build their SQL skills
[Introduction to the roadmap from a developer's perspective]
If you are a developer, I recommend following the entire roadmap.
As many developers will agree, great applications are born on top of well-designed databases. This is because there are problems in the database area that can never be solved with application code alone. This roadmap will fill in the remaining half of the core competencies and make you a higher-level developer.
Introduction : First, we will cover the basics of databases and SQL through the 'Introduction'.
Basics : The Basics covers the basic database skills that are essential for junior developers.
You will gain the ability to solve any complex business requirement in SQL using joins, subqueries, unions, and case statements.
By properly understanding the operating principles of indexes, you will learn the fundamentals of SQL performance optimization essential for practical use.
A deep understanding of transactions and data integrity enables you to build robust applications that don't corrupt data.
Design : The design section will help you become a developer at the next level. You will learn how good database design determines the maintainability and scalability of applications, and develop the ability to systematically model complex requirements that you will encounter in practice.
Performance Optimization and Advanced Features: Performance Optimization and Advanced Features is the final gateway to becoming an advanced developer handling high-volume traffic. You will master advanced techniques to find database performance bottlenecks that no one else can solve and push the limits of your services.
By mastering this roadmap, you will grow beyond being a “simple developer who implements features” to a truly capable developer who deeply understands and optimizes both the application and the database, and can find a solution to any problem.
[Introducing the roadmap from a planning and data analyst perspective]
If you are a planner or data analyst, I recommend listening to the introductory and basic versions.
Getting Started: Once you master the fundamentals of SQL with Getting Started, you'll have the speed and independence to get the answers you need immediately, without having to request data and wait.
Basics : In the Basics, we go one step further.
By using advanced SQL such as joins, subqueries, unions, and case statements, you can combine data scattered in various places, reprocess it according to your own criteria, and add depth to your analysis.
These two courses alone will transform you into a key player who can improve services based on data, persuade organizations, and communicate smoothly with development teams.
If you want to lead a data-based product yourself, it may be a good idea to take the 'Design' course as an advanced course to broaden your understanding of data structures.
For planners and analysts, this introductory and fundamentals roadmap will completely change the way you work with data.
Introduction - Section Table of Contents
1. Lecture introduction and teaching materials
2. Introduction to the database
3. Start the database
4. SQL - Data Management
5. SQL - Query and Sorting
6. SQL - Data Processing
7. SQL - Aggregation and Grouping
Basics - Section Table of Contents
1. Lecture introduction and teaching materials
2. Join 1 - Inner Join
3. Join 2 - Outer Join and Other Joins
4. Subquery
5. UNION
6. CASE statement
7. View
8. Index 1
9. Index 2
10. Data Integrity
11. Transaction
12. Stored Procedures, Functions, and Triggers
We've compiled and answered questions about the roadmap's progress.
1. Basic order of database roadmap progress
- The basic order is Java -> Database -> Spring -> Spring Boot and JPA utilization.
2. Recommended order of database roadmap progress
The most effective progression is to study the Introduction to Databases and the Fundamentals right before Spring DB1 on the Spring roadmap.
So, the learning process is as follows:
- ...
- Spring MVC2
- Introduction to Databases
- Database Basics
- Spring DB Part 1
- Spring DB Part 2
- ...
When proceeding with the roadmap for utilizing Spring Boot and JPA, it is recommended that you listen to at least the database basics and proceed.
We will provide a more comprehensive overview of database design, performance optimization, and advanced features once they are released.
3. Are you going to learn based on MySQL? Or on Oracle?
Although the practical training focuses on MySQL, the lecture content focuses on imparting general knowledge that covers not only MySQL but also the entire RDBMS. Therefore, the goal is to gain a broad understanding that is not tied to a specific database.
To use an analogy, in this lecture we will learn how to drive a car called MySQL. However, we will not simply learn how to operate a specific model of car, but will focus on learning the basic driving principles (core concepts of RDBMS) that you need to know no matter what car (RDBMS) you drive, such as the accelerator, brake, and steering wheel. So it will be of great help when dealing with other RDBMS.
thank you
･
Edited
Hello everyone. Finally, we have opened the last lecture of the Java Roadmap, Advanced Java Part 3.
Link: https://inf.run/iZKKT
Kim Young-han's Practical Java - Advanced Part 3, Lambda, Stream, Functional Programming
Lecture time: 16 hours 40 minutes
Number of lectures: 97
Lecture PDF Material: 387 pages
[Course Introduction]
Learn new syntax and techniques frequently used in modern Java, such as lambda, stream, and functional programming. In this lecture, I will teach you how to apply these techniques in practice, deeply understand them, and utilize them, beyond simply knowing them.
[Summary of lecture contents]
The main lecture contents are as follows.
1. Why Lambda is needed
Learn how lambdas play a vital role in modern Java, both for clean, concise code and for easily leveraging advanced features like parallel processing.
2. Lambda
You will learn the definition, syntax, and usage tips of lambda through real code examples. You will clearly understand how it differs from the existing method and what makes it attractive.
3. Functional interface
Functional interface, an essential concept used with lambda! We will tell you why functional programming is possible and how to easily utilize various functional interfaces built into the Java standard API.
4. Using Lambda
How can we apply lambda in practical code? Let's learn the core usage of lambda to simplify repetitive patterns and complex logic with examples.
5. Lambda vs Anonymous Class
We compare and analyze in which situations lambdas are more efficient and in which cases anonymous classes should be used.
6. Method Reference
The method reference syntax added in Java 8 takes functional programming to the next level of cleanliness. We will explain how the method reference syntax works and what are some practical examples of its use.
7. Stream API1 - Basics
The Stream API presents a new paradigm for handling Java collections with lambdas. We will organize the stream structure and basic usage in an easy-to-understand manner for beginners.
8. Stream API2 - Features
Let's take a closer look at the core features provided by streams, such as filtering, mapping, sorting, and reducing. You can learn how to write code more intuitively and concisely.
9. Stream API3 - Collector
Learn the concept of Collector, which is utilized in streams for efficient data collection and processing. You can learn essential skills in practice, such as collect(), grouping, and partitioning.
10. Optional
Let's make proper use of Optional, which cleanly resolves null handling. We will cover various methods to prevent NPE problems that are frequent in practice, such as isPresent(), orElse(), and orElseThrow().
11. Default method
Let's take a look at a new aspect of Java interfaces: default methods.
Learn the correct usage practices, along with how to maintain compatibility when extending interfaces.
12. Parallel Streams
Parallel processing for high performance! Learn about ForkJoin pools, multi-core utilization know-how through stream APIs, and precautions that may arise in parallel streams.
13. Functional Programming
All features added after Java 8, such as lambda, stream API, and Optional, reflect the functional programming paradigm. We will teach you how to write more efficient code by combining object-oriented languages and the functional paradigm.
thank you
