6.SQL Real-World Applications
1. SQL Projects – Real-World Examples
Library Management System
Track books, borrowers, and due dates using SQL queries.
— Sample table: books
CREATE TABLE books (
book_id INT PRIMARY KEY,
title VARCHAR(100),
due_date DATE,
borrower_id INT
);
— Query: Fetch overdue books
SELECT title, due_date
FROM books
WHERE due_date < CURRENT_DATE;
| Title | Due Date |
|---|---|
| SQL Fundamentals | 2023-08-01 |
| Data Science 101 | 2023-07-25 |
Salary Management System
Calculate payroll and generate reports.
— Sample table: employees
CREATE TABLE employees (
emp_id INT PRIMARY KEY,
name VARCHAR(100),
base_salary DECIMAL(10,2),
bonus DECIMAL(10,2)
);
— Query: Total compensation
SELECT name, base_salary + bonus AS total_compensation
FROM employees;
2. SQL for Data Analysts
Use SQL for reporting and generating insights.
— Monthly sales by region
SELECT region, MONTH(sale_date) AS month, SUM(amount) AS total_sales
FROM sales
GROUP BY region, MONTH(sale_date)
ORDER BY region, month;
3. SQL for Business Intelligence Tools
Connect SQL databases to Tableau and Power BI using views and stored procedures.
— Create a view for customer lifetime value
CREATE VIEW customer_ltv AS
SELECT customer_id, SUM(order_amount) AS lifetime_value
FROM orders
GROUP BY customer_id;
Use this view in Tableau or Power BI to build dashboards.
BI Dashboard Example
BI Dashboard Mockup
Practice Exercises
- Design a library schema and fetch overdue books.
- Create a salary report using joins and aggregates.
- Connect SQL to Tableau and build a dashboard.
- Identify top-performing employees via SQL.
Real-World Project Walkthrough
Employee Performance Tracker
Use SQL to rank employees based on performance metrics and visualize in BI tools.
— Rank employees by performance score
SELECT emp_id, name, performance_score,
RANK() OVER (ORDER BY performance_score DESC) AS rank
FROM employee_performance;
FAQs
How does SQL power BI tools?
SQL provides structured data through views and queries that BI tools like Tableau and Power BI use to build dashboards and reports.
What are common queries for analysts?
Analysts frequently use aggregation (`SUM`, `AVG`), filtering (`WHERE`), grouping (`GROUP BY`), and joins to generate insights.
Can SQL handle complex projects?
Yes, SQL is capable of handling complex data models, recursive queries, and integration with other tools for enterprise-level applications.