[Concept Class] SQL Queries You Can Learn and Use Immediately

hello
My name is Joe and I work as an Inflearn knowledge sharer.

It seems like the days are getting warmer. Are you taking care of your health?
I have been avoiding writing long articles using the excuse that I am not very good at writing, but today I would like to say hello under the pretense of promoting the release of a new lecture.

This email is sent through Inflearn's student mailing list, so those of you reading this are likely those who have registered for one of my courses.

Suddenly, I checked when I opened my first lecture on Inflearn, and it turned out that I opened my first SQL lecture in the winter of December 2020. I've been running lectures for five years, so some people might not remember my nickname, or they might have registered for the lecture last month and are looking into it. But it's all okay. I'm grateful to them all, and I'm curious about how they're developing.

I have no doubt that students have experienced many changes, but the past five years have also brought about many changes for me. In the past five years, my engineer identity has become stronger than before, a book I wrote myself has been published, I have moved three times, and the company I have worked for has changed. I have created lectures, but I have also become a student of other knowledge sharers, and I think I have thought about what capabilities I should further develop.

It was probably the same when I first gave the lecture, but I didn't have high expectations at the beginning. At first, I thought I could just make the lectures that were being given offline online and organize them, but I didn't know it would last this long. I guess you never know what will happen with people.

After that, it became an opportunity for the book <Planner's SQL> to be published without a hitch, and it also gave me the strength to create other lectures. Although there were times when I stopped working for a while, I was able to continue my activities for five years thanks to the students who registered for my lectures.

What are you interested in these days, students? These days, I am interested in the changes brought about by AI. However, as I started making online lectures for the past five years, I am worried about what kind of knowledge will still be valid in the era of advanced AI. I still don't know the right answer, but I think that fundamental knowledge will continue to survive in the future. Since this is an era where questions are important, I think that the basic knowledge for asking questions will still be alive.

I'm still making lectures that I want to make, and the lecture I brought this time is a lecture that briefly explains the basics of Python grammar and uses the AI code generation IDE, Cursor, to create code directly . I think it would be good for beginners to quickly see the basics without much expectation, as it is 2 hours long, and I plan to continuously update the use cases in the future. To commemorate the release of the lecture, we are also holding a 90% discount for exactly one month, so please refer to it if you need it.

Link: https://inf.run/4HYsY

I will continue to work on finding topics that I can do well in the future and developing lectures that are easy and contain only the necessary parts. As we approach the full-blown summer, please be careful of the heat, and I will always support you so that you can gradually achieve your goals for this year.

thank you
Joe Dream

PS -1
We are planning a lecture completion challenge. If you would like to receive challenge notifications, please sign up for the waiting list below to receive notifications more quickly.

PS -2
Have you ever wanted to create a lecture?
I am thinking about running a challenge where I can help people who want to experience creating lectures. If you are interested in creating lectures, please register on the waiting list below.

Register for the challenge waiting list:

https://forms.gle/E3gCL3onxjdh6YDr9

hello.

This is Joe, running a data lecture.

Today, in the irregular newsletter, I am sharing with you the information I found out after seeing the emergence of AI and the recent active research on libraries such as Text-To-SQL, wondering , "What is the overseas data scene doing now?"

This article is a translation and summary of Datacamp's Data & AI Trends & Predictions 2025 White Paper.

2025, 5 Key Trends in Overseas Data Scene AI & Data

1. The boundaries between data professions are blurred.

As AI automates SQL and data analytics tasks, the traditional role distinctions between data analysts, engineers, and data scientists are blurring.

Now, all professions must be able to handle data, and data literacy (the ability to read and utilize data) is becoming more important.

2. AI research continues to advance, but actual adoption is slow

AI models are becoming more powerful, but actual adoption of AI within enterprises remains slow

It is predicted that more than 30% of Generative AI projects will be abandoned by 2025 (Gartner)

The key task is not simply to improve AI model performance, but how to link it with actual business processes.

3. The differentiating point of AI tools will be the user experience (UX).

As the performance gap between AI models narrows, user experience (UI/UX) and actual usability become more important competitive factors.

AI research labs are thinking about how to make it more intuitive and easier to use.

The goal is to make AI an essential tool for business operations, not just a technology.

4. AI & Data Skills Gap is still a major issue

The gap in AI and data utilization capabilities remains a major issue within companies

For companies, educating employees to handle AI and data is becoming a more urgent task than introducing AI.

5. In an era where AI writes SQL instead, data literacy becomes important.

As AI-based Text-to-SQL technology advances, data extraction through SQL becomes easier

However, this does not mean that you do not need to know SQL, but rather that the ability to interpret and utilize SQL has become more important.

AI generates and interprets SQL, but it’s still up to humans to plan what data to analyze

source:

https://www.datacamp.com/report/data-trends-predictions-2025

Thank you for reading.

Joe Dream

@Thread: https://www.threads.net/@breachers_data

@Instagram: https://www.instagram.com/breachers_data

hello

This is Joe, who runs data-related lectures at Infraon.

< Announcing the publication of the planner's SQL 📢 >

On June 20th, a book titled <Planner's SQL> for those who are new to SQL was published . 🎉 Rather than looking at SQL from the perspective of a traditional developer, the book was written with great care in the composition and order of the content so that even beginners can easily approach it. Thanks to the hard work of the publisher Insight 💪 , the cover design was chosen very pretty, so please show a lot of interest 🙏

Go to buy books (Kyobo Bookstore):

https://product.kyobobook.co.kr/detail/S000213474520

<Book Review Event 🎉 >

To celebrate the publication, I will select 5 people who need a SQL book and send them a free book (I will pay for the shipping). If you or a student need SQL, please fill out the survey by 5:00 PM on Friday, November 22nd through the survey link below!

Survey Link:

https://forms.gle/x2ZCatxH3kwL4br46

• We would like to ask the winners to write a brief review as shown below. Please refer to the example link. Thank you. 🙇 🙇 🙇

  • Example review:

    https://blog.naver.com/choiiing/223634700539

We sincerely support the growth of our students.

thank you

Joe Dream

Q. I need to query a DB I have never seen before. Is there a standard for understanding the data?

- As in the lecture, you need to check the data by sampling only some of the data by setting a limit or using top, etc.

- But this alone is often not enough. Even when looking at sample data, there are times when it is unclear what the data is.

- The conditions that determine what data are 1) schema and 2) row occurrence rules .

- A schema is a blueprint for the table structure, including what columns there are and what data types the columns allow.

- A row occurrence rule refers to the rule for when a data row occurs in the table and when the trigger occurs.

- This is something that everyone who has ever run a query up to the schema has kept in mind.

- Surprisingly, it is easy to miss what the rules for occurrence are. These are usually determined by the backend server.

- For example, in the case of an order table, normally one row may be created when one order occurs.

- When an order is cancelled, it is necessary to clearly understand the rules for whether the existing order row is modified or a new row is created.

- These rules may be somewhat difficult to verify because they are part of the backend developer developing WAS or analyzing the backend source code.

- Since it is a very important part that determines the format of the data, it is important to know it when looking at a new DB for reliable analysis, right? :-)

* This is a new post where we share answers to frequently asked questions about SQL.

Q. Which SQL query is the most readable?

- This is a question I get asked often.

- But there is no right answer. This is because everyone has a different style of writing code.

- There is no set format, but each team or company can create and use its own rules.

- These are usually called code conventions, style guides, etc., and can be applied to SQL as well.

- For example, languages like Python have their code conventions internalized into the language's operational syntax.

- No one is the best, but there are definitely some SQL code conventions that are more commonly read.

- Below are links to the code conventions (most of which are in English).

- I will update this later with a lecture :)

Mozilla (Firefox) SQL Style Guide:

https://docs.telemetry.mozilla.org/concepts/sql_style.html

Gitlab SQL Style Guide:

https://about.gitlab.com/handbook/business-technology/data-team/platform/sql-style-guide/

Simon Holywell's SQL Style Guide:

https://www.sqlstyle.guide/

* This is a new post where we share answers to frequently asked questions about SQL.

Introduction to Google Big Query & Data Pipe Architecture Content

- I found some useful content for those who have studied SQL and want to study data more, so I am sharing it with you through news.

- This video covers the concepts and practical use of Google Big Query, which is widely used as a data lake/warehouse.

- This is educational content conducted directly by Google Korea headquarters, and you can view it for free through the link below.

- You will get a feel for how the modern data pipeline architecture is structured, not just BigQuery.

- Also covers general concepts about DB (e.g. normalization)

link:

https://cloudonair.withgoogle.com/events/korea-cloud-onboard-dwh-online-2021

hello

This is Joe, teaching SQL :-)

It's already the last day of 2020 after a turbulent year, and I have mixed feelings about it. I wonder how you, the learners, are wrapping up the year-end.

Like everyone else, 2020 was a year of many changes for me, and starting to teach SQL was one of them.

It started with SQL classes taught by in-house staff at Startup Cremon, which led to giving lectures at other companies and even the opportunity to meet students online.

While taking offline classes, I was proud to see people who didn't know SQL gradually improve and now directly handle data in the company's DB. I think that joy is what gives me the strength to continue teaching SQL 💪

Although we won't be able to meet in person online, please feel free to send me any questions you may have through Infraon. Our lectures also run a Slack channel, so please come in and ask questions.

Well, I hope you all finish the year well, and I'll be back next year with good lecture updates :D

Happy New Year everyone!

Joe Dream