This module covers relational databases, ER modeling, functional dependencies, normalization, and managing data coherence, integrity, and constraints.

Become a Database Professional with SQL

In this interactive module, you’ll learn the fundamentals of relational databases and explore relational design and mapping.

You'll start with an overview of relational databases and database keys, then explore concepts like functional dependencies and normalization (1NF, 2NF, 3NF) to improve data consistency, coherence, and efficiency. As you progress, you'll explore integrity rules, constraints, and data modeling using entity-relationship diagrams (ERD) to a relational schema. You'll then apply key SQL concepts, including data manipulation, CSV to SQL import, aggregate functions, SQL joins, and subqueries.

By the end of this module, you'll be able to design efficient databases and write optimized SQL queries for real-world applications.

Relational Database Model

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Excel-Like Data Viewer</title>
    <link rel="stylesheet" href="styles.css">
</head>
<body>

    <h1>Online Store Excel Sheet</h1>

    <div class="tabs">
        <button class="tab-button active" onclick="showTab('customers')">Customers</button>
        <button class="tab-button" onclick="showTab('products')">Products</button>
        <button class="tab-button" onclick="showTab('orders')">Orders</button>
    </div>

    <div id="customers" class="tab-content">
        <h2>Customers</h2>
        <table id="customersTable">
            <thead>
                <tr>
                    <th>Customer ID</th>
                    <th>Name</th>
                    <th>Email</th>
                    <th>Address</th>
                </tr>
            </thead>
            <tbody>
                
            </tbody>
        </table>
    </div>

    <div id="products" class="tab-content" style="display: none;">
        <h2>Products</h2>
        <table id="productsTable">
            <thead>
                <tr>
                    <th>Product ID</th>
                    <th>Name</th>
                    <th>Price</th>
                    <th>Stock</th>
                </tr>
            </thead>
            <tbody>
                
            </tbody>
        </table>
    </div>

    <div id="orders" class="tab-content" style="display: none;">
        <h2>Orders</h2>
        <table id="ordersTable">
            <thead>
                <tr>
                    <th>Order ID</th>
                    <th>Customer ID</th>
                    <th>Product ID</th>
                    <th>Quantity</th>
                </tr>
            </thead>
            <tbody>
                
            </tbody>
        </table>
    </div>

    <script src="script.js"></script>

</body>
</html>

// Sample data for Customers, Products, and Orders
const customers = [
    { id: 1, name: "Emily Clark", email: "emily1@example.com", address: "123 Main St" },
    { id: 2, name: "John Doe", email: "john@example.com", address: "456 Oak St" },
    { id: 3, name: "Alice Smith", email: "alice@example.com", address: "789 Pine St" },
    { id: 4, name: "Emily Clark", email: "emily1@example.com", address: "123 Main St" },
    { id: 5, name: "David Wilson", email: "david@example.com", address: "654 Cedar St" }
];

const products = [
    { id: 1, name: "Wireless Earbuds", price: 49.99, stock: 15 },
    { id: 2, name: "Smartwatch", price: 199.99, stock: 8 },
    { id: 3, name: "Gaming Mouse", price: 29.99, stock: 12 },
    { id: 4, name: "Wireless Earbuds", price: 45.99, stock: 20 } // Duplicate product with a different price
];

const orders = [
    { orderId: 101, customerId: 1, productId: 2, quantity: 1 },
    { orderId: 102, customerId: 4, productId: 1, quantity: 2 }, // Emily Clark's duplicate entry
    { orderId: 103, customerId: 3, productId: 3, quantity: 1 },
    { orderId: 104, customerId: 1, productId: 4, quantity: 1 } // Different price issue
];

// Function to populate tables
function populateTable(tableId, data) {
    const tableBody = document.querySelector(`#${tableId} tbody`);
    tableBody.innerHTML = ""; // Clear previous data
    data.forEach(item => {
        let row = "<tr>";
        for (let key in item) {
            row += `<td>${item[key]}</td>`;
        }
        row += "</tr>";
        tableBody.innerHTML += row;
    });
}

// Function to switch between tabs
function showTab(tabName) {
    document.querySelectorAll(".tab-content").forEach(tab => tab.style.display = "none");
    document.getElementById(tabName).style.display = "block";

    document.querySelectorAll(".tab-button").forEach(button => button.classList.remove("active"));
    document.querySelector(`[onclick="showTab('${tabName}')"]`).classList.add("active");
}

// Populate tables on load
populateTable("customersTable", customers);
populateTable("productsTable", products);
populateTable("ordersTable", orders);


body {
    font-family: Arial, sans-serif;
    text-align: center;
    margin: 20px;
    background-color: #f4f4f4;
}

h1 {
    color: #333;
}

.tabs {
    margin-bottom: 20px;
}

.tab-button {
    padding: 10px 20px;
    margin: 5px;
    cursor: pointer;
    border: none;
    background-color: #007BFF;
    color: white;
    border-radius: 5px;
}

.tab-button.active {
    background-color: #0056b3;
}

.tab-content {
    margin: auto;
    width: 80%;
    background-color: white;
    padding: 20px;
    border-radius: 8px;
    box-shadow: 0px 0px 10px rgba(0, 0, 0, 0.1);
}

table {
    width: 100%;
    border-collapse: collapse;
    margin-top: 10px;
}

th, td {
    border: 1px solid #ddd;
    padding: 10px;
    text-align: center;
}

th {
    background-color: #007BFF;
    color: white;
}


codemirror

Learn why we need database modeling and how to design.

Relational Database and Normalization

Relational Model

Data Manipulation

Conclusion

What Is a Relational Database?

When spreadsheets fail

What went wrong?