🧪 Real-world SQL Scenarios & Challenges
Let’s dive into the types of real-world problems you’ll encounter as a data analyst, data scientist , data engineer, or developer.
1. Finding Duplicates
SELECT name, COUNT(*)
FROM employees
GROUP BY name
HAVING COUNT(*) > 1;
Perfect for data cleaning and validation tasks.
2. Get the Second Highest Salary
SELECT MAX(salary) AS second_highest
FROM employees
WHERE salary < (
SELECT MAX(salary)
FROM employees
);
3. Running Totals
SELECT name, salary,
SUM(salary) OVER (ORDER BY id) AS running_total
FROM employees;
Essential in dashboards and financial reports.
4. Customers with No Orders
SELECT c.customer_id, c.name
FROM customers c
LEFT JOIN orders o ON c.customer_id = o.customer_id
WHERE o.order_id IS NULL;
Very common in e-commerce or CRM platforms.
5. Monthly Aggregates
SELECT DATE_TRUNC('month', order_date) AS month,
COUNT(*) AS total_orders
FROM orders
GROUP BY month
ORDER BY month;
Great for trends and time-based reporting.
6. Pivot-like Output (Using CASE)
SELECT
department,
COUNT(CASE WHEN gender = 'Male' THEN 1 END) AS male_count,
COUNT(CASE WHEN gender = 'Female' THEN 1 END) AS female_count
FROM employees
GROUP BY department;
Super useful for dashboards and insights.
7. Recursive Queries (Org Hierarchy or Tree)
WITH RECURSIVE employee_tree AS (
SELECT id, name, manager_id
FROM employees
WHERE manager_id IS NULL
UNION ALL
SELECT e.id, e.name, e.manager_id
FROM employees e
INNER JOIN employee_tree et ON e.manager_id = et.id
)
SELECT * FROM employee_tree;
Used in advanced data modeling and tree structures.
You don’t just need to know how SQL works — you need to know when to use it smartly!
React with ❤️ if you’d like me to explain more data analytics topics
Share with credits: https://news.1rj.ru/str/sqlspecialist
SQL Roadmap: https://news.1rj.ru/str/sqlspecialist/1340
Hope it helps :)
Let’s dive into the types of real-world problems you’ll encounter as a data analyst, data scientist , data engineer, or developer.
1. Finding Duplicates
SELECT name, COUNT(*)
FROM employees
GROUP BY name
HAVING COUNT(*) > 1;
Perfect for data cleaning and validation tasks.
2. Get the Second Highest Salary
SELECT MAX(salary) AS second_highest
FROM employees
WHERE salary < (
SELECT MAX(salary)
FROM employees
);
3. Running Totals
SELECT name, salary,
SUM(salary) OVER (ORDER BY id) AS running_total
FROM employees;
Essential in dashboards and financial reports.
4. Customers with No Orders
SELECT c.customer_id, c.name
FROM customers c
LEFT JOIN orders o ON c.customer_id = o.customer_id
WHERE o.order_id IS NULL;
Very common in e-commerce or CRM platforms.
5. Monthly Aggregates
SELECT DATE_TRUNC('month', order_date) AS month,
COUNT(*) AS total_orders
FROM orders
GROUP BY month
ORDER BY month;
Great for trends and time-based reporting.
6. Pivot-like Output (Using CASE)
SELECT
department,
COUNT(CASE WHEN gender = 'Male' THEN 1 END) AS male_count,
COUNT(CASE WHEN gender = 'Female' THEN 1 END) AS female_count
FROM employees
GROUP BY department;
Super useful for dashboards and insights.
7. Recursive Queries (Org Hierarchy or Tree)
WITH RECURSIVE employee_tree AS (
SELECT id, name, manager_id
FROM employees
WHERE manager_id IS NULL
UNION ALL
SELECT e.id, e.name, e.manager_id
FROM employees e
INNER JOIN employee_tree et ON e.manager_id = et.id
)
SELECT * FROM employee_tree;
Used in advanced data modeling and tree structures.
You don’t just need to know how SQL works — you need to know when to use it smartly!
React with ❤️ if you’d like me to explain more data analytics topics
Share with credits: https://news.1rj.ru/str/sqlspecialist
SQL Roadmap: https://news.1rj.ru/str/sqlspecialist/1340
Hope it helps :)
❤4👍2
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Master the most in-demand AI skill in today’s job market: building autonomous AI systems.
In Ready Tensor’s free, project-first program, you’ll create three portfolio-ready projects using 𝗟𝗮𝗻𝗴𝗖𝗵𝗮𝗶𝗻, 𝗟𝗮𝗻𝗴𝗚𝗿𝗮𝗽𝗵, and vector databases — and deploy production-ready agents that employers will notice.
Includes guided lectures, videos, and code.
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1. Python for Beginners
🔗https://learn.microsoft.com/en-us/training/paths/beginner-python/
2. Introduction to Machine Learning with Python
🔗https://learn.microsoft.com/en-us/training/paths/intro-to-ml-with-python/
3. Microsoft Azure AI Fundamentals
🔗 https://learn.microsoft.com/en-us/training/paths/get-started-with-artificial-intelligence-on-azure/
4. Write Your First Code Using C#
🔗https://learn.microsoft.com/en-us/training/paths/get-started-c-sharp-part-1/
5. Get started with AI on Azure
🔗https://learn.microsoft.com/en-us/training/modules/get-started-ai-fundamentals/
6. Microsoft Azure Fundamentals: Describe Cloud Concepts
🔗https://learn.microsoft.com/en-us/training/paths/microsoft-azure-fundamentals-describe-cloud-concepts/
7. Introduction to GitHub
🔗https://learn.microsoft.com/en-us/training/modules/introduction-to-github/
8. Build an Early-Stage Startup
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9. Microsoft Search Fundamentals
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10. Get Started with Office 365
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11. Data Science for Beginners
🔗https://microsoft.github.io/Data-Science-For-Beginners/#/
Enjoy Learning 🌟
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10 Microsoft courses you DO NOT want to miss ⬇️
1. Python for Beginners
🔗https://learn.microsoft.com/en-us/training/paths/beginner-python/
2. Introduction to Machine Learning with Python
🔗https://learn.microsoft.com/en-us/training/paths/intro-to-ml-with-python/
3. Microsoft Azure AI Fundamentals
🔗 https://learn.microsoft.com/en-us/training/paths/get-started-with-artificial-intelligence-on-azure/
4. Write Your First Code Using C#
🔗https://learn.microsoft.com/en-us/training/paths/get-started-c-sharp-part-1/
5. Get started with AI on Azure
🔗https://learn.microsoft.com/en-us/training/modules/get-started-ai-fundamentals/
6. Microsoft Azure Fundamentals: Describe Cloud Concepts
🔗https://learn.microsoft.com/en-us/training/paths/microsoft-azure-fundamentals-describe-cloud-concepts/
7. Introduction to GitHub
🔗https://learn.microsoft.com/en-us/training/modules/introduction-to-github/
8. Build an Early-Stage Startup
🔗https://learn.microsoft.com/en-us/training/paths/startups/
9. Microsoft Search Fundamentals
🔗https://learn.microsoft.com/en-us/training/paths/microsoft-search-fundamentals/
10. Get Started with Office 365
🔗https://learn.microsoft.com/en-us/training/paths/get-started-office-365-windows/
11. Data Science for Beginners
🔗https://microsoft.github.io/Data-Science-For-Beginners/#/
Enjoy Learning 🌟
❤7
Java project ideas to help you practice your skills
1. ToDo List Application: Create a command-line or GUI-based application that allows users to create, manage, and organize their tasks.
2. Calculator: Build a simple calculator application that can perform basic arithmetic operations like addition, subtraction, multiplication, and division.
3. Library Management System: Design a system for managing library resources, including books, patrons, and borrowing records.
4. Chat Application: Develop a chat application that enables users to communicate in real-time, either as a desktop app or through a web interface.
5. Weather App: Create an app that fetches weather data from an API and displays current weather conditions for a given location.
6. Student Gradebook: Build a program to store and calculate student grades. You can add features like grade averages and report generation.
7. Expense Tracker: Create an application for tracking expenses and generating reports, helping users manage their finances.
8. Simple Game (e.g., Tic-Tac-Toe): Implement a classic game like Tic-Tac-Toe to learn about game logic and user interaction.
9. Blog or Content Management System (CMS): Build a simple blog or CMS where users can create, edit, and publish articles.
10. E-commerce Shopping Cart: Create a basic online shopping cart system with product listings, a shopping cart, and checkout functionality.
11. File Manager: Develop a file manager application that allows users to organize and manage files and directories on their computer.
12. Inventory System: Design an inventory management system for tracking products, quantities, and orders for a small business.
13. Music Player: Create a basic music player with features like play, pause, skip, and a library of songs.
14. Password Manager: Build a secure application for storing and managing passwords and other sensitive information.
15. Chess or Sudoku Solver: Implement a chess game or a Sudoku puzzle solver to delve into complex algorithms and logic.
16. Note-taking App: Develop a note-taking application with features like creating, editing, and organizing notes.
17. Expense Sharing App: Build an app for groups to track shared expenses and split bills among friends or roommates.
18. Task Scheduler: Create a program that allows users to schedule and manage tasks, reminders, and appointments.
19. Mini Social Media Platform: Create a simplified social media platform with features like user profiles, posting, and commenting.
20. Quiz or Flashcard Application: Design an app for creating and taking quizzes or using flashcards to study various topics.
Choose a project that aligns with your interests and skill level. As you work on these projects, you'll gain valuable experience and improve your Java programming skills.
1. ToDo List Application: Create a command-line or GUI-based application that allows users to create, manage, and organize their tasks.
2. Calculator: Build a simple calculator application that can perform basic arithmetic operations like addition, subtraction, multiplication, and division.
3. Library Management System: Design a system for managing library resources, including books, patrons, and borrowing records.
4. Chat Application: Develop a chat application that enables users to communicate in real-time, either as a desktop app or through a web interface.
5. Weather App: Create an app that fetches weather data from an API and displays current weather conditions for a given location.
6. Student Gradebook: Build a program to store and calculate student grades. You can add features like grade averages and report generation.
7. Expense Tracker: Create an application for tracking expenses and generating reports, helping users manage their finances.
8. Simple Game (e.g., Tic-Tac-Toe): Implement a classic game like Tic-Tac-Toe to learn about game logic and user interaction.
9. Blog or Content Management System (CMS): Build a simple blog or CMS where users can create, edit, and publish articles.
10. E-commerce Shopping Cart: Create a basic online shopping cart system with product listings, a shopping cart, and checkout functionality.
11. File Manager: Develop a file manager application that allows users to organize and manage files and directories on their computer.
12. Inventory System: Design an inventory management system for tracking products, quantities, and orders for a small business.
13. Music Player: Create a basic music player with features like play, pause, skip, and a library of songs.
14. Password Manager: Build a secure application for storing and managing passwords and other sensitive information.
15. Chess or Sudoku Solver: Implement a chess game or a Sudoku puzzle solver to delve into complex algorithms and logic.
16. Note-taking App: Develop a note-taking application with features like creating, editing, and organizing notes.
17. Expense Sharing App: Build an app for groups to track shared expenses and split bills among friends or roommates.
18. Task Scheduler: Create a program that allows users to schedule and manage tasks, reminders, and appointments.
19. Mini Social Media Platform: Create a simplified social media platform with features like user profiles, posting, and commenting.
20. Quiz or Flashcard Application: Design an app for creating and taking quizzes or using flashcards to study various topics.
Choose a project that aligns with your interests and skill level. As you work on these projects, you'll gain valuable experience and improve your Java programming skills.
❤6