[CS Technical Interview 4] Database That Makes You Speak Fluently

🥲 Getting a developer job, coding tests weren't the end of it.

As a non-major, when I first prepared for developer employment, I 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 the lack of CS (Computer Science) knowledge. In interviews, CS fundamentals were considered much more important than algorithms.

🗣 For actual interviews, 'speaking practice' was important.

Even after filling in my CS fundamentals, interviews were still not easy. During an interview at a certain company, I was asked about floating-point numbers. It was content I thought I had read and understood multiple times in books, but I couldn't utter a single word. That's when I realized it. Passive learning through simply reading and understanding cannot provide answers 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 practicing to organize concepts in just a few sentences and articulate them out loud. Through this process, you can also discover what you didn't know precisely. Without sufficient practice, you'll encounter the following problems.

1. Conceptual Confusion Type

❓InterviewerWhat are the characteristics of object-oriented programming?
💬 Candidate The SOLID principles. First, S is..(omitted)...

This is a case of confusing similar concepts.
SOLID is an OOP design principle, and the characteristics of object-oriented programming are abstraction, encapsulation, inheritance, and polymorphism.
The moment you mix up related concepts, the interviewer judges that 'your fundamentals are shaky'.
It's not just a simple mistake, but it's read as a signal that your conceptual framework is not solidly established.

2. Lack of Specificity Type

❓Interviewer What are the characteristics of TCP?
💬 Candidate It's a protocol that guarantees reliability.
❓ Interviewer What are the mechanisms that guarantee reliability?
💬 Candidate Uh... well... it makes transmission safe... like that...

This is a case where you only know the What, but are missing the How/Why.
You only know the superficial answers and aren't prepared to explain the underlying principles.
TCP establishes communication through connection (3-way handshake), ensures reliability through RDT (sequence numbers, ACK, retransmission, etc.), and maintains quality through flow control and congestion control.
These concepts need to be connected as one cohesive flow in your mind. Without organizing concepts concretely, you cannot prepare for follow-up questions.

3. Getting tongue-tied on basic questions

❓Interviewer What is HTTP?
💬 Candidate Um... it's for sending and receiving data on the web... something like that...?

It's such a familiar concept, but when asked to explain it in one sentence, the words don't come easily.
Words like request, response, server, and client come to mind, but they don't flow naturally into a coherent sentence.
This is because we've never practiced explaining from definition to principles in one continuous flow.
This isn't a lack of knowledge, but an absence of structure.

Just knowing is not enough. It only becomes true skill when you can express it in words.

🔥 That's why I created it. The CS Technical Interview Series That Gets You Talking!

🎯 Recommended for these people

Non-majors · Job seekers · Career changers and others who are preparing for technical interviews and need to be able to organize CS fundamentals verbally

⚡ Lecture Core Kick

💡 Use it like this

💬 Q. The lecture time is short, but will I be able to learn properly?

🖐 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 have been more confident than anyone in combining and reconstructing various materials to create 'my own comprehensive study notes'. This lecture is precisely that 'ultimate self-study know-how' and a secret notebook born from all my passion and philosophy.

🔥 What makes this course special?

• All of my 'know-how' is included: As a non-CS major who self-studied CS and programming languages and got hired at a large corporation, I've fully incorporated my experiences and know-how. I've put all the methods for how to most efficiently understand complex and abstract concepts and make them your own into this course.

• '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.

🚀 Introducing the fourth lecture [Database] edition of Tech 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 understood that sharding is vertical partitioning and partitioning is horizontal partitioning❓

• Or do you know that indexes are good for performance, but their complex structure and operating principles are still confusing❓

This course is a CS lecture designed for exactly 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 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 with a focus on practical application.

• Why do we perform normalization, and how far should we go?
  → Explains anomalies and 1st to 3rd normalization stages, as well as denormalization, with 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, clustering vs non-clustering index comparisons, and more 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 it be prevented?
  → 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 these core questions that frequently appear in technical interviews 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.

✏ Here's what you'll learn

👀 Course Preview

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

🔗 Technical Interview Master Roadmap

Pre-enrollment Reference Information