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SQL/DB Basics You Should Know Before Asking AI

If you ask an AI to "get the top 10 sales," it will whip up a plausible-looking query in no time. However, to determine if that query is actually correct, if the results of joining three tables are accurate, or if it's performing a full scan on 500,000 records without an index—you ultimately need a foundation in DB basics. This course doesn't cover anything overly difficult. In just 2 hours, you will learn the entire flow of SQL by coding along, covering exactly what you need to know before giving instructions to an AI. By the end of this lecture, you will no longer feel uneasy when faced with a query generated by AI.

(5.0) 22 reviews

766 learners

Level Beginner

Course period Unlimited

MySQL
MySQL
DBMS/RDBMS
DBMS/RDBMS
database
database
AI
AI
AX(Agent Experience)
AX(Agent Experience)
MySQL
MySQL
DBMS/RDBMS
DBMS/RDBMS
database
database
AI
AI
AX(Agent Experience)
AX(Agent Experience)

Reviews from Early Learners

Reviews from Early Learners

5.0

5.0

므갱이

100% enrolled

This is a great course if you just want to quickly grasp the basics of databases and SQL statements to the point of saying, "Ah, so that's what this is." While you'll need to study the fine details on your own, this course shows you exactly what and how to study. (For example, it helps beginners identify things they don't understand even after using various commands, or figure out what a "procedure" is... it helps you find your own path for further study.) It packs more information than expected into a short, intensive format. Considering the Notion summary materials and the fact that it's free, I think it's a truly excellent course!

5.0

원승언

93% enrolled

I took this course to review my DB knowledge, and it was very detailed and easy to understand. I also loved that it was free. Although it was short, it was great to be able to learn the core concepts.

5.0

clscls2530

100% enrolled

The overall knowledge of SQL was explained in an easy-to-understand way, so I was able to follow along well.

What you will gain after the course

  • Interview confidence in "DB basics"

  • An environment where I can run SQL directly on my computer.

  • Fundamentals for using CRUD and JOIN fluently

  • 'SQL verification skills' to read and judge queries written by AI

Can you judge whether the query written by AI is correct?

When you say, "Pull this data for me," AI generates plausible-looking SQL. It handles SELECT, JOIN, and GROUP BY all on its own. It’s actually quite good at it. But the problem comes afterward. You JOINed three tables and the data volume exploded—is that correct? The AI tells you to add an index, but you don't know what an index is. "It works for now, so let's just use it" → and then the server crashes in production.


If you lack basic DB concepts, using AI actually becomes more dangerous.

That's why I created this course. We skip the complex theories and start with the "why" from everyday life.
🍜 What kind of data makes up a restaurant page on Naver Maps?
🎮 Why doesn't the MapleStory trade window have bugs where money only disappears from one side?
📚 How can you find the book you want from among 500,000 books in just 0.1 seconds?

Installation → Table Creation → Data CRUD → JOIN → Transaction → Index. You will learn the entire flow of SQL by coding along within 2 hours. By the end of the course, you will reach a level where you can look at a query generated by AI and judge whether "this is correct" or "this is wrong."


What you will gain from this course

The ability to verify queries written by AI

After asking the AI to "extract this data," you will be able to personally judge whether the resulting query is correct or incorrect. You will be able to check for yourself whether the JOINs are correct, if the WHERE conditions match your intent, and even if an index is required.

Setting up the MySQL + DBeaver environment

Windows/Mac installation guides provided & even how to execute SQL using GUI tools

Summary of Core Database Concepts

Relationships between tables, records, primary keys (PK), and foreign keys (FK)
1:1, 1:N, M:N associations and JOIN utilization
Transaction ACID (Easily understood with a MapleStory trade window example)

Hands-on Performance Optimization Practice

Generating 500,000 mock data records
Performance comparison before and after applying indexes (274ms → 69ms)
Concepts of composite indexes and cardinality

Solving Programmers SQL Problems

Practice types that appear in actual coding tests
Utilizing AVG, ROUND, GROUP BY, and HAVING

Here is what you will learn.

Learning databases easily with real-life examples

  • Understanding the identity of data through a Naver restaurant page

  • Relational vs. Non-relational DB: When to use which?

  • From installing MySQL + DBeaver to connecting them


Mastering the Basics of Tables and SQL

  • Learning the concepts of tables, records, and keys using school data

  • Creating a database and making your first table

  • Inserting and retrieving data with INSERT and SELECT

Completing CRUD and Connecting Tables with JOIN

  • Updating and deleting data with UPDATE and DELETE

  • Learning 1:N and M:N relationships through teacher-student examples

  • Combining tables with LEFT JOIN and INNER JOIN

  • Extracting the data you want with GROUP BY and subqueries

DB visualization videos that are immediately understood upon seeing

  • What exactly are CRUD and Join?

  • It's confusing when you read it in writing, but you'll understand it in 3 seconds when you see it in an animated video.

  • We present it through visualization videos so you can clearly picture it in your mind.

Recommended for the following people

🎯 Those learning SQL for the first time

Non-majors who haven't taken a database
course
Those who want to start from "what is a table" and "what is a record"

🎯 Those who have learned but haven't organized their knowledge

Those who learned quickly at a bootcamp but haven't grasped the overall flow. Those who can perform CRUD operations but don't know what transactions or indexes are.

🎯 Those who asked AI to write SQL but don't know if the results are correct

Those who have asked ChatGPT or Claude to write a query but can't judge whether the result is correct or not. Those who feel anxious, thinking, "I ran it for now, but something seems off..."



🎁 EVENT 🎁

There is a special benefit provided only to those who take the course.

DB completion summary worksheets are provided

(This workbook is provided as a Notion link!)

Get it after verifying your course review!

(I have included the instructions on how to verify in the very last lecture __)

The person who created this course

Sharing the behind-the-scenes story of reaching the final interviews at Coupang and Yanolja - A 6th-year developer's 24-company job-hopping story [ep 5]

Dingco Dingco (Main Instructor)

  • 2021 ~ 2022: S Coding Club Algorithm (data-structure) Tutor

  • 2022 ~ : Operating the coding YouTube channel Dingco Dingco (Featuring various content related to developer employment)

  • 2022 ~ 2023: Viva Republica Server Developer


  • Never giving up on a student 🦈

  • Operating a developer career-cracking community and organizing offline meetups


Notes before taking the course

Learning Materials

  • Lecture notes are provided via a Notion link. Feel free to refer back to them whenever you review!

Prerequisites and Notices

📌 Required: None

I will teach you step-by-step, starting from the MySQL installation. You will learn about DBMS/RDBMS!
You can follow along even if you have no prior programming experience.

📌 Nice to have:

If you have experience with any programming language (Python, Java, JavaScript, etc.)
Basic concepts such as "variables" and "conditional statements"

Recommended for
these people

Who is this course right for?

  • Non-developer roles working at an IT company

  • People who want to create various queries using AI

  • Those who asked AI to write SQL but are unable to verify the results.

Need to know before starting?

  • No need! If you know how to turn on a computer and use a web browser, you're all set.

Hello
This is dingcodingco

15,331

Learners

1,572

Reviews

295

Answers

4.9

Rating

18

Courses

🚀 Former Toss, POSTECH graduate | Current Backend Developer (+8 years)
🎥 YouTuber with 20,000 subscribers | Development content creator
📚 Inflearn Instructor | Over 15,000+ cumulative students
👥 Running a developer career community (8,000+ members)
🧩 Contributor to various open-source projects (Gradle, Spring AI, etc.)
📝 Passed 38 resume screenings and conducted 100+ resume reviews on Kmong (5.0 rating)

I deliver vivid, real-world industry insights in an easy and deductively understandable way.
Tôi truyền tải những thông tin thực tế từ ngành một cách dễ hiểu và có hệ thống.

Inflearn Interview Link!

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Reviews

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22 reviews

5.0

22 reviews

  • dnjstmddjs126599님의 프로필 이미지
    dnjstmddjs126599

    Reviews 7

    Average Rating 5.0

    5

    93% enrolled

    I took this course to review my DB knowledge, and it was very detailed and easy to understand. I also loved that it was free. Although it was short, it was great to be able to learn the core concepts.

    • jpt2518님의 프로필 이미지
      jpt2518

      Reviews 6

      Average Rating 4.8

      5

      36% enrolled

      • min3939176277님의 프로필 이미지
        min3939176277

        Reviews 6

        Average Rating 4.8

        Edited

        5

        100% enrolled

        This is a very helpful lecture for those who are new to SQL. The explanations using various analogies and examples help with understanding.

        • clscls25308891님의 프로필 이미지
          clscls25308891

          Reviews 1

          Average Rating 5.0

          Edited

          5

          100% enrolled

          The overall knowledge of SQL was explained in an easy-to-understand way, so I was able to follow along well.

          • meustar829님의 프로필 이미지
            meustar829

            Reviews 30

            Average Rating 4.8

            Edited

            5

            100% enrolled

            This is a great course if you just want to quickly grasp the basics of databases and SQL statements to the point of saying, "Ah, so that's what this is." While you'll need to study the fine details on your own, this course shows you exactly what and how to study. (For example, it helps beginners identify things they don't understand even after using various commands, or figure out what a "procedure" is... it helps you find your own path for further study.) It packs more information than expected into a short, intensive format. Considering the Notion summary materials and the fact that it's free, I think it's a truly excellent course!

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