[CS Technical Interview Part 4] Database Made Easy

🚀 Introducing the fourth lecture [Database] edition of the Technical Interview Master Roadmap.

📕 Database: Bridging the Gap Between 'Theory' and 'Practice'!

Databases are an essential technology used in all areas of development, but for many beginners, they often learn only SQL while the theoretical concepts behind it feel vague and unclear.

• You know SQL syntax, but find it difficult to explain the deep reasons why you should use JOIN❓

• You can't remember the transaction isolation levels well, and you don't know what problems are solved at each level❓

• Haven't you just roughly assumed that sharding is vertical partitioning and partitioning is horizontal partitioning❓

• Do you know that indexes are good for performance, but are still puzzled by their complex structure and operating principles❓

This course is a CS lecture designed specifically for those people, bridging the gap between practical SQL application and interview theory. It explains concepts with flow through diagrams and examples, focusing on the 'Why' of each concept so you can easily understand and remember them for a long time. I strongly recommend this course to those who have done basic coding but found databases overwhelming, and those who want to systematically organize CS theory.

🎯 Through this course, you will be able to clearly answer the following questions.

• Why do we need databases?
  → We explain DBMS/RDBMS concepts, table structure, and modeling reasons from the ground up.

• How is SQL structured, and what syntax is mainly used in practice?
  → We'll organize the flow from basic SELECT to JOIN, paging queries, and advanced SQL, focusing on practical application.

• Why do we perform normalization, and how far should we go?
  → We'll explain anomalies and the 1st to 3rd normalization stages, as well as denormalization, focusing on practical examples.

• What is a transaction, in what situations is it needed, and what are the differences between isolation levels?
  → We will cover transaction states, ACID, the characteristics of each isolation level and the problems they solve along with real-world examples.

• How do indexes work structurally, and why do they affect performance?
  → We'll organize B-Tree index structures, composite indexes, comparison of clustered and non-clustered indexes, etc. for practical preparation.

• When do you use sharding and partitioning?
  → Intuitively explains large-scale processing and data distribution strategies, delivering clear concepts of vertical/horizontal partitioning.

• Why does SQL Injection occur, and how can we defend against it?
  → Explains concepts like input validation and Prepared Statements from a practical perspective.

📌 At the end of the course, a practical interview practice chapter awaits you.

"What is a transaction and why are ACID principles important?", "Does using indexes always make things faster? Please explain the advantages, disadvantages, and types of indexes", "In what situations are normalization and denormalization each necessary?" - you can now practice answering core questions that frequently appear in technical interviews like these fluently on your own in just one or two sentences.

📖 A curriculum packed with only the essentials

This is the table of contents and key keywords you will learn in this course.

If there are any unfamiliar keywords, make sure to grasp them thoroughly this time.

💡 Non-majors can also succeed in developer jobs - CS is the key!

"I thought it would be over once I passed the coding test. But it wasn't."

I too, when first preparing for a developer job, was obsessed only with algorithms and coding tests. I gained some confidence and passed most coding tests. However, I kept failing at the next hurdle - technical interviews.
What was the problem?

It was precisely the lack of CS (Computer Science) knowledge. In interviews, CS fundamentals were considered much more important than algorithms. However, there was no need to dive deep into every CS subject. There were separate core CS concepts that frequently appear in technical interviews.

This course is a roadmap that systematically organizes those scattered core CS knowledge pieces. For those who, like me as a non-CS major, experienced frustration, I've clearly organized complex CS theories with a flow-centered approach. Furthermore, I've included core question practice chapters to help you develop the 'ability to explain' required in technical interviews. Now it's time to transform into a real developer through complete CS mastery.

✏ Here's what you'll learn

👀 Course Preview

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🖐 Hello! Let me introduce myself! 🙇

I created this course thinking of my past self, who stayed up all night worrying about fundamentals and felt anxious over every single interview question.

I started as a non-CS major and understand better than anyone the thirst for fundamentals (CS knowledge, programming languages, etc.). Through self-studying countless materials and building my own know-how, I eventually graduated from Seoul National University and now work as a 🧑🏻‍💻 Kakao developer.

Since childhood, I've been more confident than anyone in combining and reconstructing various materials to create 'my own comprehensive study notes.' This course is precisely that 'ultimate self-study secret note' born from all my passion and philosophy.

🔥 What makes this course special?

• All of my 'know-how' is included: As a non-major, I have fully incorporated my experience and know-how of self-studying CS and programming languages and getting hired at a large corporation. I have included in this course all the methods for how to most efficiently understand complex and abstract concepts and make them your own.

• 'Fundamentals' are key in any development field: Whether you're aiming for game development, AI, web/app development, or any other field, basic computer science knowledge is not optional but essential. This course helps you become a true expert based on solid fundamentals.

• We compete with 'overwhelming quality': I've referenced countless materials including textbooks, famous university lectures, commercial books, and technical interview resources to extract core keywords and reconstruct them in my own unique way. With intuitive diagrams and illustrations, combined with easy explanations infused with my practical experience, I promise to make even complex concepts click with that "Ah, now I get it!" moment.

  
  

🗣 Real Interview Practice: Why is 'Speaking Practice' Important? (My Vivid Experience)

Let me share my experience with you. In an interview at a certain company, I was asked a question about floating-point numbers. I was sure I had read about it multiple times in books and thought I understood it, but I couldn't utter a single word. I painfully realized that simply reading and understanding through passive learning wasn't enough to answer questions in real interviews.

You've probably experienced this at least once. You definitely studied and understood well, but because you didn't organize individually and practice 'speaking', all that effort was useless in real situations.

To succeed in interviews, you need not only to accumulate a lot of knowledge but also the ability to explain this knowledge. This 'ability to explain' can only be developed through practice of organizing concepts in just a few sentences and speaking them out loud. Through this process, you can also discover what you didn't know precisely.

My course doesn't miss this crucial point. After learning each core concept, we'll practice together in the 'Interview Practice' chapter where we practice summarizing in a few simple sentences that fit the interview format. Through this course, I will personally help ensure your knowledge shines in front of the interviewer. ✨

💡 Curious about other interview preparation courses? Check out the roadmap below :)

Pre-enrollment Reference Information