📦 Exercise Files

📖 MOST COMMON SQL INTERVIEW QUESTION

Do you knew this?

👉 “What is the order of execution in an SQL query?”

Don’t let the SELECT fool you – it’s NOT the first step! 😮
Here’s the correct order that SQL follows behind the scenes:

🔢 SQL Order of Execution:
1️⃣ FROM
2️⃣ JOIN
3️⃣ WHERE
4️⃣ GROUP BY
5️⃣ HAVING
6️⃣ SELECT
7️⃣ DISTINCT
8️⃣ ORDER BY
9️⃣ LIMIT / OFFSET

🔥 Pro tip: Interviewers LOVE this question to test your SQL fundamentals!
Memorize it, understand it – and impress in your next interview. 💼

📖 Data Analyst

📖 Data Visualisation CheatSheet

🔅 The 80/20 Rule of Data Science

📝 Explore the core concepts of the 80/20 rule for data science and how to get most of the value with minimal effort.

🌐 Author: Howard Friedman
🔰 Level: Intermediate
⏰ Duration: 1h 26m

📋 Topics: Data Science, Project Engineering, Team Management

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📱Data Science
📱The 80/20 Rule of Data Science

📖 4 Main in Database Types

📖 SQL Learning Roadmap — 8 Key Steps:

1. Basic:
Start by understanding what SQL is, why it’s used, and the different types of SQL commands (DDL, DML, DCL, TCL). This builds your foundation.

2. Queries:
Learn how to fetch data using commands like SELECT, FROM, WHERE, ORDER BY, and LIMIT. Practice filtering data with operators such as =, !=, LIKE, IN, and BETWEEN.

3. Joins:
To work with multiple tables, you must understand INNER, LEFT, RIGHT, and FULL OUTER JOIN. Know how primary and foreign keys relate tables.

4. Functions:
Use built-in functions like COUNT, SUM, AVG, MIN, and MAX for data analysis. Learn how to group data using GROUP BY and filter groups with HAVING.

5. Subqueries:
Write queries within queries! Learn scalar, correlated, and multi-row subqueries. They’re powerful for solving complex data problems.

6. Data Manipulation:
Master how to change data using INSERT, UPDATE, and DELETE. Also, understand transactions using BEGIN, COMMIT, and ROLLBACK to maintain data integrity.

7. Advanced:
Take it further with window functions (ROW_NUMBER, RANK, LEAD, LAG), CTEs (WITH), views, and indexing to write efficient and optimized queries.

8. Practice:
The final step is consistent practice. Work with real-world datasets, focus on query optimization, and solve challenges on platforms like LeetCode, Mode, or HackerRank.