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Kim Young-han's Practical Database - Fundamentals

Learn the essential fundamentals of SQL and databases needed for practical work. Not only developers, but also product managers and data analysts can learn SQL in depth.

(5.0) 306 reviews

3,315 learners

Level Basic

Course period Unlimited

  • yh
SQL
SQL
MySQL
MySQL
DBMS/RDBMS
DBMS/RDBMS
SQLD
SQLD
SQL
SQL
MySQL
MySQL
DBMS/RDBMS
DBMS/RDBMS
SQLD
SQLD

Reviews from Early Learners

Reviews from Early Learners

5.0

5.0

개foot

20% enrolled

Wow.... I'm a current developer. Please upload the next episode within a month..... Otherwise I'll get sulky I'm going crazy watching the lectures because they're so good...... I was already thinking that the importance of SQL? Performance and tuning would be important these days, but starting from the basics with practical tips and step-by-step explanations at such depth, it's an honor to be taking such a good lecture in Korea. I recommend it to others too!!

5.0

jjs270402

7% enrolled

As a job seeker, your lectures are really helping me a lot. This database series is no exception. I can't wait to eagerly learn the next lecture as soon as possible. Thank you always for your passionate lectures :)

5.0

Seung Min Liang

43% enrolled

Since I haven't done Java before, this is my first time taking a lecture. Now I understand why you're such a popular instructor. Please release the next episode as soon as possible...

What you will gain after the course

  • Understanding Basic Concepts and Structure of Relational Databases

  • SQL Core Syntax and Key Query Utilization (JOIN, Subquery, UNION, CASE, VIEW, etc.)

  • Index Optimization for High-Performance Queries (Covering & Composite Indexes)

  • Finding Optimal Index Structure and Design Principles Through Execution Plan Analysis

  • Transaction and Integrity Management for Stable Data Processing

#1 in cumulative students in Korea's development field,
Kim Young-han's Practical Database

Trendy technology? What's more important is database fundamentals!

Former Woowa Brothers Technical Director, Over 500,000 Students
Why Kim Young-han Created a Database Course

•••

"I wanted to create a database course that contains the fundamentals truly needed in real-world practice."

Practical Database Skills That Make the Difference

Many developers treat databases as simple storage, only repeating create, update, read, and delete operations. While they know about JOIN and INDEX, they often don't properly understand why they're necessary.

However, if JOIN configurations or INDEX settings are inadequate, the service gradually slows down and eventually leads to failures. In fact, since 90% of failures originate from database issues, databases are at the core of development.

Good design and queries
start with the fundamentals.

Ultimately, a developer's skills are complete only when both coding ability and database management skills are developed together.
In particular, since a poorly designed database structure is difficult to change later, it is more important than anything to build a solid foundation from the start.

That's why this course doesn't just teach SQL syntax.

Beyond simply knowing SQL syntax, this course is designed to help you clearly understand the underlying principles, and develop the ability to independently judge and design optimal SQL for different data structures and situations.

This fundamental course is the most important course that serves as the backbone of the roadmap, containing only the minimum essential database fundamentals you need to know.

This course is for all job roles, not just developers.

For analysts, planners, and marketers, SQL is no longer optional. It's becoming increasingly important to improve services based on data, persuade organizations, and communicate smoothly with development teams. Just knowing the core features covered in this course, anyone can read and interpret data and connect it to practical insights.

Kim Young-han's Practical Database Roadmap

This course is the second course in the Practical Database Roadmap, designed to help all IT professionals systematically learn the essential database fundamentals needed in real-world practice.

Introduction to Roadmap Courses and Guide Videos

Frame 66

Roadmap Series Part 2, Database Fundamentals

6 Core SQL Topics for Practical Work

Join

In the basics course, we'll first dive deep into joins, which are called the flower of relational databases. Starting from why they're needed, through inner, outer, and self joins, we'll show you through practical examples what to use in which situations.

Subqueries

Next, we'll cover subqueries and clearly explain what many people find confusing—the differences between subqueries and joins, and when to use each for better performance.

UNION, CASE, VIEW

Gather scattered data through UNION, classify and process the necessary data based on conditions using CASE statements. Through VIEWs, you can save your complex SQL with a simple name.

Index

Indexes, the key factor that determines service speed. Beyond simple syntax explanations, we cover the structure and principles of how indexes enable fast searches, as well as practical optimization techniques such as covering indexes and composite indexes. Furthermore, we provide clear guidance on how to design and effectively utilize indexes.

Transactions, Data Integrity

We also cover in depth transactions and data integrity that ensure data consistency. We'll help you build a solid foundation on why concurrency control is necessary and what ACID is.

Stored Procedures, Functions, Triggers

Finally, we'll briefly look at how to utilize logic within databases such as stored procedures, functions, and triggers. We'll also explore why these features are rarely used in modern practice and what alternatives exist in contemporary application development.

A course that's exceptional from the basics
Proven by 500,000+ students.

⭐⭐⭐⭐⭐

I was often moved by the step-by-step sequence and materials that could only come from thinking deeply from a beginner's perspective. Just as your current courses did for me, I hope you continue to create courses that can extend a helping hand to those who are lost and struggling like I was back then. Thank you!

"Spring Boot - Core Principles and Practical Application"
Course Reviews

⭐⭐⭐⭐⭐️

I only knew how to do CRUD, and when I occasionally encountered DB issues, even after googling, the knowledge was fragmented and seemed to have gaps somewhere, but this lecture fills those gaps. ... I guess fundamentals are important after all. And I don't think there's anyone who teaches those fundamentals as well as Younghan-nim.

"Spring DB Part 1 - Core Principles of Data Access" Course Review

⭐⭐⭐⭐⭐

It's truly the best. While taking other courses, I had questions like "Why is it used this way?" and things that left me with unresolved doubts, and questions I had while self-studying like "Why does this part work this way??" are all explained clearly and concisely. ... If you've had experiences where you couldn't cleanly resolve your questions while studying alone, I highly recommend this. I'm really looking forward to the intermediate and advanced courses as well.

"Kim Young-han's Practical Java - Basic Edition"
Course Reviews

⭐⭐⭐⭐⭐

Throughout the lecture, opening the web browser developer tools and showing how things actually work became an opportunity for me to gain more interest by understanding that the parts I'm actually studying work like that. ... Please continue to upload many lectures and spread positive influence to many people. Thank you for the great lecture. ^^

"HTTP Web Basics for All Developers" Course Reviews

⭐⭐⭐⭐⭐

I'm truly grateful for the practical lectures and detailed explanations you provide, and your thoughtfulness in explaining things one more time that you've covered before. ... Due to the limitations of government-funded education, I couldn't let myself fall apart like this, and while searching, I found your lectures which seem like they will change my life. With the goal of working at the same company as you as a developer, I will work hard to become a competent developer. Thank you sincerely.

"Spring Core Principles - Basic Edition" Course Reviews

⭐⭐⭐⭐⭐

I was able to get a big picture of what I could build with Spring, and rather than just teaching the technology outright, you showed how inefficiencies or problems arise while writing code and explained that these technologies were introduced to solve them, building it up naturally from start to finish, which allowed me to learn smoothly!

"Introduction to Spring - Learn Spring Boot, Web MVC, and DB Access Technologies through Code"Course Review

Recommended for
these people

Who is this course right for?

  • Job seeker preparing for a developer position

  • Developers who have studied databases but want to properly solidify their fundamentals

  • Planners, marketers, and data analysts who want to learn SQL

  • Everyone in the IT industry

Need to know before starting?

  • Kim Young-han's Practical Database Introduction - Starting from SQL Step by Step

  • Basic SQL usage including SELECT, GROUP BY, and HAVING

Hello
This is

576,409

Learners

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Reviews

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Answers

5.0

Rating

26

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My goal is to provide education so that you can become a true developer with skills actually needed in the field..

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Curriculum

All

84 lectures ∙ (13hr 40min)

Course Materials:

Lecture resources
Published: 
Last updated: 

Reviews

All

306 reviews

5.0

306 reviews

  • dirend79555님의 프로필 이미지
    dirend79555

    Reviews 51

    Average Rating 5.0

    5

    20% enrolled

    Wow.... I'm a current developer. Please upload the next episode within a month..... Otherwise I'll get sulky I'm going crazy watching the lectures because they're so good...... I was already thinking that the importance of SQL? Performance and tuning would be important these days, but starting from the basics with practical tips and step-by-step explanations at such depth, it's an honor to be taking such a good lecture in Korea. I recommend it to others too!!

    • yh
      Instructor

      Thank you, 개foot :) I put a lot of thought into focusing on explanations of content essential for practical work rather than covering everything, and I appreciate you recognizing these aspects. I wish you joyful studies and significant growth! I cheer you on!

  • jjs2704023067님의 프로필 이미지
    jjs2704023067

    Reviews 28

    Average Rating 5.0

    5

    7% enrolled

    As a job seeker, your lectures are really helping me a lot. This database series is no exception. I can't wait to eagerly learn the next lecture as soon as possible. Thank you always for your passionate lectures :)

    • yh
      Instructor

      I'm cheering for jjs270402 to study hard and achieve the goals you're aiming for!

  • liang님의 프로필 이미지
    liang

    Reviews 3

    Average Rating 5.0

    5

    43% enrolled

    Since I haven't done Java before, this is my first time taking a lecture. Now I understand why you're such a popular instructor. Please release the next episode as soon as possible...

    • yh
      Instructor

      It was worth all the hard work you put into preparing this, Seung Min Liang :) You can look forward to the next design section the most^^ Thank you.

  • applepy8099님의 프로필 이미지
    applepy8099

    Reviews 8

    Average Rating 5.0

    Edited

    5

    100% enrolled

    I'm happy

    • yh
      Instructor

      I'm happy as well, thanks to you, applepy :)

  • slothmaru님의 프로필 이미지
    slothmaru

    Reviews 13

    Average Rating 4.4

    5

    100% enrolled

    I am a working backend developer. Everything I feel when watching your lectures can be summarized in one word: "Empathy." I relate to every single thing you say, and I strongly agree with your point about Java vs. DB—that if the DB is well-designed and structured, the difficulty of development significantly decreases. Compared to your other courses, this one took me a bit longer to get through and was more challenging to understand. However, being able to firmly grasp the fundamental principles of how subqueries work made the course worth the purchase alone, and you've truly opened my eyes to indexes. I will continue to follow your lectures and strive to become a better developer. Thank you for the great course.

    • yh
      Instructor

      slothmaru, I love the expression "empathy." In fact, I created this lecture based on things I felt were absolutely essential to know in order to grow quickly in the field, save time, and avoid unnecessary struggles. I think that's why it resonates with you. Have a happy 2026! :)

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