1. Employees and Departments Tables

Table: Employees

Table: Departments

Question: Find the total salary expenditure for each department.

SQL Query:

SELECT d.DepartmentName, SUM(e.Salary) AS TotalSalary
FROM Employees e
JOIN Departments d ON e.DepartmentID = d.DepartmentID
GROUP BY d.DepartmentName;
    

2. Orders and Customers Tables

Table: Orders

Table: Customers

Question: Retrieve the total amount spent by each customer, along with their name and country.

SQL Query:

SELECT c.Name, c.Country, SUM(o.Amount) AS TotalSpent
FROM Orders o
JOIN Customers c ON o.CustomerID = c.CustomerID
GROUP BY c.Name, c.Country;
    

3. Products, Sales, and Categories Tables

Table: Products

Table: Sales

Table: Categories

Question: Calculate the total revenue generated by each category.

SQL Query:

SELECT c.CategoryName, SUM(s.Quantity * p.Price) AS TotalRevenue
FROM Sales s
JOIN Products p ON s.ProductID = p.ProductID
JOIN Categories c ON p.CategoryID = c.CategoryID
GROUP BY c.CategoryName;
    

4. Students, Courses, and Enrollments Tables

Table: Students

Table: Courses

Table: Enrollments

Question: List the names of students and the courses they are enrolled in.

SQL Query:

SELECT s.Name, c.CourseName
FROM Enrollments e
JOIN Students s ON e.StudentID = s.StudentID
JOIN Courses c ON e.CourseID = c.CourseID;
    

5. Books, Authors, and BookAuthors Tables

Table: Books

Table: Authors

Table: BookAuthors

Question: List the titles of books and their authors.

SQL Query:

SELECT b.Title, a.Name
FROM BookAuthors ba
JOIN Books b ON ba.BookID = b.BookID
JOIN Authors a ON ba.AuthorID = a.AuthorID;