Greetings, SQL enthusiasts and eager learners! Today, we delve into the world of SQL assignments, unraveling complex queries, and providing insightful solutions. At programminghomeworkhelp.com, our mission is to empower students with the knowledge and skills necessary to conquer SQL challenges confidently. Whether you're a novice or an experienced coder, our SQL assignment help service is here to guide you through the intricacies of database management.

Question 1: Analyzing Sales Data

Consider a scenario where you're tasked with analyzing sales data from a retail database. You need to retrieve the top 5 best-selling products along with their sales revenue for the current year. Additionally, you must display the percentage of total sales revenue each product contributes.

Solution:

SELECT 
    product_id,
    product_name,
    SUM(quantity * unit_price) AS total_sales,
    SUM(quantity * unit_price) / (SELECT SUM(quantity * unit_price) FROM sales WHERE YEAR(sale_date) = YEAR(CURRENT_DATE())) * 100 AS percentage_of_total
FROM 
    products
JOIN 
    sales ON products.id = sales.product_id
WHERE 
    YEAR(sale_date) = YEAR(CURRENT_DATE())
GROUP BY 
    product_id, product_name
ORDER BY 
    total_sales DESC
LIMIT 5;

In this solution:

• We use a JOIN operation to combine the products and sales tables based on the common product_id.
• The SUM() function calculates the total sales revenue for each product.
• We utilize a subquery to calculate the total sales revenue for the current year.
• Finally, we present the top 5 best-selling products along with their respective sales revenue and percentage of total sales.

Question 2: Employee Hierarchy Analysis

Imagine you're working with an employee database that stores hierarchical data using the adjacency list model. Your task is to retrieve the names of all employees along with their respective manager's name.

Solution:

WITH RECURSIVE EmployeeHierarchy AS (
    SELECT 
        id,
        name,
        manager_id
    FROM 
        employees
    WHERE 
        manager_id IS NULL -- Assuming top-level managers have NULL manager_id
    UNION ALL
    SELECT 
        e.id,
        e.name,
        e.manager_id
    FROM 
        employees e
    INNER JOIN 
        EmployeeHierarchy eh ON e.manager_id = eh.id
)
SELECT 
    e.name AS employee_name,
    m.name AS manager_name
FROM 
    EmployeeHierarchy e
LEFT JOIN 
    employees m ON e.manager_id = m.id;

In this solution:

• We utilize a Common Table Expression (CTE) with the RECURSIVE keyword to traverse the employee hierarchy recursively.
• The initial query selects top-level managers.
• The recursive part joins employees with their respective managers.
• Finally, we retrieve the names of all employees along with their manager's name using a LEFT JOIN operation.

With these expertly crafted solutions, you can approach SQL assignments with confidence and finesse. Remember, mastering SQL is not just about writing queries; it's about understanding data relationships and leveraging the power of SQL to extract meaningful insights.

At programminghomeworkhelp.com, we're dedicated to your success. Whether you need assistance with SQL assignments or want to deepen your understanding of database management, our team of experts is here to support you every step of the way.