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

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

As someone from a non-computer science background, when I first prepared for a developer job, I focused solely on 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 not easy. At a certain company's interview, I was asked about floating point. 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 practice of organizing concepts into just a few sentences and speaking 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 unstable.'
It's not just a simple mistake, but it's read as a signal that the conceptual framework is not established.

2. Lack of Specificity Type

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

This is a case where you only know the What, but the How/Why is missing.
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 should be connected as one coherent flow in your mind. Without organizing concepts concretely, you cannot prepare for follow-up questions.

3. Getting tongue-tied with 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 articulate CS fundamentals verbally

⚡ Lecture Core Kick

📘 Technical Interview Practical WorkbookProvided

💡 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 while 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 know better than anyone the thirst for fundamentals (CS knowledge, programming languages, etc.). After diving into countless materials through self-study 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 secret note born from my 'ultimate self-study know-how' and 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, plus 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 the Technical Interview Master Roadmap.

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

Databases are essential technology used in all development fields, 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 learned 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 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 organize the practical application flow from basic SELECT to JOIN, paging queries, and advanced SQL.

• 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?
  → Transaction states, ACID, characteristics of each isolation level and the problems they solve are structured 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.

• SQL Injection occurs due to lack of input validation and can be defended against through input validation and Prepared Statement concepts, etc., explained from a practical perspective.
  → Input validation, Prepared Statement concepts, etc. are explained from a practical standpoint.

📌 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 an index 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 firmly this time around.

✏ Here's what you'll learn

👀 Course Preview

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💡 Curious about another interview preparation course? Please refer to the roadmap below :)

🔗 Technical Interview Master Roadmap

Pre-enrollment Reference Information