Data Engineers
Free Data Engineering Ebooks & Courses
Show more๐ Analytical overview of Telegram channel Data Engineers
Channel Data Engineers (@sql_engineer) in the English language segment is an active participant. Currently, the community unites 10 379 subscribers, ranking 19 346 in the Education category and 40 072 in the India region.
๐ Audience metrics and dynamics
Since its creation on ะฝะตะฒัะดะพะผะพ, the project has demonstrated rapid growth, gathering an audience of 10 379 subscribers.
According to the latest data from 09 June, 2026, the channel demonstrates stable activity. Although there has been a change in the number of participants by 243 over the last 30 days and by 11 over the last 24 hours, overall reach remains high.
- Verification status: Not verified
- Engagement rate (ER): The average audience engagement rate is 10.19%. Within the first 24 hours after publication, content typically collects N/A% reactions from the total number of subscribers.
- Post reach: On average, each post receives 1 057 views. Within the first day, a publication typically gains 0 views.
- Reactions and interaction: The audience actively supports content: the average number of reactions per post is 7.
- Thematic interests: Content is focused on key topics such as sql, learning, analytic, engineer, link:-.
๐ Description and content policy
The author describes the resource as a platform for expressing subjective opinions:
โFree Data Engineering Ebooks & Coursesโ
Thanks to the high frequency of updates (latest data received on 10 June, 2026), the channel maintains relevance and a high level of publication reach. Analytics show that the audience actively interacts with content, making it an important point of influence in the Education category.
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I am seeking to become an expert professional in [Making ChatGPT prompts perfectly]. I would like ChatGPT to provide me with a complete course on this subject, following the principles of Pareto principle and simulating the complexity, structure, duration, and quality of the information found in a college degree program at a prestigious university. The course should cover the following aspects: Course Duration: The course should be structured as a comprehensive program, spanning a duration equivalent to a full-time college degree program, typically four years. Curriculum Structure: The curriculum should be well-organized and divided into semesters or modules, progressing from beginner to advanced levels of proficiency. Each semester/module should have a logical flow and build upon the previous knowledge. Relevant and Accurate Information: The course should provide all the necessary and up-to-date information required to master the skill or knowledge area. It should cover both theoretical concepts and practical applications. Projects and Assignments: The course should include a series of hands-on projects and assignments that allow me to apply the knowledge gained. These projects should range in complexity, starting from basic exercises and gradually advancing to more challenging real-world applications. Learning Resources: ChatGPT should share a variety of learning resources, including textbooks, research papers, online tutorials, video lectures, practice exams, and any other relevant materials that can enhance the learning experience. Expert Guidance: ChatGPT should provide expert guidance throughout the course, answering questions, providing clarifications, and offering additional insights to deepen understanding. I understand that ChatGPT's responses will be generated based on the information it has been trained on and the knowledge it has up until September 2021. However, I expect the course to be as complete and accurate as possible within these limitations. Please provide the course syllabus, including a breakdown of topics to be covered in each semester/module, recommended learning resources, and any other relevant information
(Tap on above text to copy)SELECT name, email FROM users;
This fetches only the name and email columns from the users table.
โ๏ธ Used when you donโt want all columns from a table.
2๏ธโฃ Filter Records with WHERE
SELECT * FROM users WHERE age > 30;
The WHERE clause filters rows where age is greater than 30.
โ๏ธ Used for applying conditions on data.
3๏ธโฃ ORDER BY Clause
SELECT * FROM users ORDER BY registered_at DESC;
Sorts all users based on registered_at in descending order.
โ๏ธ Helpful to get latest data first.
4๏ธโฃ Aggregate Functions (COUNT, AVG)
SELECT COUNT(*) AS total_users, AVG(age) AS avg_age FROM users;
Explanation:
- COUNT(*) counts total rows (users).
- AVG(age) calculates the average age.
โ๏ธ Used for quick stats from tables.
5๏ธโฃ GROUP BY Usage
SELECT city, COUNT(*) AS user_count FROM users GROUP BY city;
Groups data by city and counts users in each group.
โ๏ธ Use when you want grouped summaries.
6๏ธโฃ JOIN Tables
SELECT users.name, orders.amount
FROM users
JOIN orders ON users.id = orders.user_id;
Fetches user names along with order amounts by joining users and orders on matching IDs.
โ๏ธ Essential when combining data from multiple tables.
7๏ธโฃ Use of HAVING
SELECT city, COUNT(*) AS total
FROM users
GROUP BY city
HAVING COUNT(*) > 5;
Like WHERE, but used with aggregates. This filters cities with more than 5 users.
โ๏ธ **Use HAVING after GROUP BY.**
8๏ธโฃ Subqueries
SELECT * FROM users
WHERE salary > (SELECT AVG(salary) FROM users);
Finds users whose salary is above the average. The subquery calculates the average salary first.
โ๏ธ Nested queries for dynamic filtering9๏ธโฃ CASE Statementnt**
SELECT name,
CASE
WHEN age < 18 THEN 'Teen'
WHEN age <= 40 THEN 'Adult'
ELSE 'Senior'
END AS age_group
FROM users;
Adds a new column that classifies users into categories based on age.
โ๏ธ Powerful for conditional logic.
๐ Window Functions (Advanced)
SELECT name, city, score,
RANK() OVER (PARTITION BY city ORDER BY score DESC) AS rank
FROM users;
Ranks users by score *within each city*.
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