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Expand Up @@ -5919,6 +5919,17 @@ <h5>Why is 2NF Not Enough?</h5>
</pre>
</section>

<section>
<h5>Does City Depend on State?</h5>
<p><span class="highlight">State depends on City</span>, not the other way around.</p>
<ul>
<li>Each <span class="highlight">city</span> belongs to one state</li>
<li>A <span class="highlight">state</span> has many cities</li>
<li>Knowing the city → you can find the state</li>
<li>Knowing the state → you cannot find a unique city</li>
</ul>
</section>

<section>
<h5>Third Normal Form (3NF)</h5>
<ul>
Expand Down Expand Up @@ -5953,7 +5964,328 @@ <h6>Cities (New Table)</h6>
</pre>
</div>
</div>
</section>
</section>

<section>
<p>A table in NF1 is in <span class="highlight">3NF</span> if all <span class="highlight">non-key
attributes</span> depend only on the primary key (NF2) and do not depend on other non-key attributes
(NF3).</p>
</section>

<section>
<h5>Second Normal Form (2NF) to Third Normal Form (3NF)</h5>
<table>
<thead>
<tr>
<th>Step</th>
<th>Description</th>
<th>Example</th>
</tr>
</thead>
<tbody>
<tr>
<td>1. Identify transitive dependencies</td>
<td>Find attributes that depend on a non-key attribute instead of the primary key</td>
<td>❌ customer_id → city → state</td>
</tr>
<tr>
<td>2. Remove transitive dependencies</td>
<td>Move dependent attributes to a separate table</td>
<td>✔ Create "Cities" table with city → state</td>
</tr>
<tr>
<td>3. Ensure direct dependency</td>
<td>All non-key attributes must depend only on the primary key</td>
<td>❌ customer_id → city → state → ✔ Store city_id in "Customers"</td>
</tr>
<tr>
<td>4. Split into separate tables</td>
<td>Move transitive dependencies to their own entities</td>
<td>✔ Customers, Orders, and Cities as separate tables</td>
</tr>
<tr>
<td>5. Use foreign keys</td>
<td>Link tables using primary and foreign keys</td>
<td>✔ customers.city_id → cities.city_id</td>
</tr>
</tbody>
</table>
</section>

<section>
<h5>History of Third Normal Form (3NF)</h5>
<ul>
<li><span class="highlight">1971</span> – Edgar F. Codd introduces 3NF to remove transitive dependencies
</li>
<li>1980s – 3NF becomes widely adopted to improve data integrity</li>
<li><span class="highlight">1990s</span> – SQL databases implement 3NF as a best practice</li>
<li>2000s-Present – 3NF remains a standard, though often denormalized for performance</li>
</ul>
</section>

<section>
<h5>Database Normal Forms</h5>
<table>
<thead>
<tr>
<th>Normal Form</th>
<th>Summmary</th>
</tr>
</thead>
<tbody>
<tr>
<td><span class="highlight">1NF</span></td>
<td>Eliminate repeating groups; ensure atomic values</td>
</tr>
<tr>
<td><span class="highlight">2NF</span></td>
<td>Remove partial dependencies; all attributes must depend on the whole primary key</td>
</tr>
<tr>
<td>3NF</td>
<td>Remove transitive dependencies; non-key attributes must depend only on the primary key</td>
</tr>
<tr>
<td>BCNF</td>
<td>Every determinant must be a candidate key; stricter than 3NF</td>
</tr>
<tr>
<td>4NF</td>
<td>Eliminate multi-valued dependencies; each row represents a single fact</td>
</tr>
<tr>
<td>5NF</td>
<td>Decompose tables to remove redundancy while preserving all joins</td>
</tr>
</tbody>
</table>
</section>

<section>
<h5>Questions?</h5>
</section>

<section>
<h5>Unnormalized, 1NF, 2NF, or 3NF?</h5>
<div style="display: flex; gap: 20px; justify-content: center; flex-direction: row;">
<div>
<h6>Orders</h6>
<pre>
+----------+------------+-----------------------+
| order_id | customer | products |
+----------+------------+-----------------------+
| 1 | Alice | Laptop, Mouse |
| 2 | Bob | Phone, Charger |
+----------+------------+-----------------------+
</pre>
</div>
</div>
</section>

<section>
<h5>Unnormalized, 1NF, 2NF, or 3NF?</h5>
<div style="display: flex; gap: 20px; justify-content: center; flex-direction: row;">
<div>
<h6>Orders</h6>
<pre>
+----------+-----------+-------------+
| order_id | customer | product_id |
+----------+------------+------------+
| 1 | Alice | 101 |
| 1 | Alice | 102 |
| 2 | Bob | 103 |
| 2 | Bob | 104 |
+----------+-----------+-------------+
</pre>
</div>
</div>
</section>

<section>
<h5>Unnormalized, 1NF, 2NF, or 3NF?</h5>
<div style="display: flex; gap: 20px; justify-content: center; flex-direction: row;">
<div>
<h6>Orders</h6>
<pre>
+----------+------------+----------+-------+
| order_id | customer | product | city |
+----------+------------+----------+-------+
| 1 | Alice | Laptop | NY |
| 1 | Alice | Mouse | NY |
| 2 | Bob | Phone | CA |
| 2 | Bob | Charger | CA |
+----------+------------+----------+-------+
</pre>
</div>
</div>
</section>

<section>
<h5>Unnormalized, 1NF, 2NF, or 3NF?</h5>
<div style="display: flex; gap: 20px; justify-content: center; flex-direction: row;">
<div>
<h6>Customers</h6>
<pre>
+------------+----------------+-------------+-------+---------+
| customer_id| phone | city | state | zip_code|
+------------+----------------+-------------+-------+---------+
| 1 | 123-456-7890 | New York | NY | 10001 |
| 3 | 987-654-3210 | Los Angeles | CA | 90001 |
+------------+----------------+-------------+-------+---------+
</pre>
</div>
<div>
<h6>Orders</h6>
<pre>
+----------+-------------+
| order_id | customer_id |
+----------+-------------+
| 1 | 1 |
| 2 | 3 |
+----------+-------------+
</pre>
</div>
</div>
</section>

<section>
<h5>Unnormalized, 1NF, 2NF, or 3NF?</h5>
<div style="display: flex; gap: 20px; justify-content: center; flex-direction: row;">
<div>
<h6>Customers</h6>
<pre>
+------------+----------------+---------+
| customer_id| phone | city_id |
+------------+----------------+---------+
| 1 | 123-456-7890 | 101 |
| 3 | 987-654-3210 | 102 |
+------------+----------------+---------+
</pre>
</div>
<div>
<h6>Cities</h6>
<pre>
+---------+-------------+---------+
| city_id | city | zip_code |
+---------+-------------+---------+
| 101 | New York | 10001 |
| 102 | Los Angeles| 90001 |
+---------+-------------+---------+
</pre>
</div>
</div>
</section>

<section>
<h5>Questions?</h5>
</section>

<section>
<h5>Database Engineering Process in Practice</h5>
<div
style="display: flex; flex-direction: row; gap: 10px; border: 2px solid black; padding: 15px; width: fit-content;">
<pre class="highlight">
+------+
| Data | -->
+------+
</pre>
<pre>
+--------------+
| Requirements | -->
+--------------+
</pre>
<pre>
+-----+
| ERD | -->
+-----+
</pre>
<pre>
+----------+
| Database | -->
+----------+
</pre>
<pre>
+-------+
| Table |
+-------+
</pre>
</div>
</section>

<section>
<h5>Discussion: When to Normalize or denormalize?</h5>
</section>

<section>
<h5>Questions?</h5>
</section>

<section>
<h5>Recursive JOINS</h5>
</section>

<section>
<h5>Sample Data: Car Parts Hierarchy</h5>
<pre>
+---------+------------+---------------+
| part_id | name | parent_part_id|
+---------+------------+---------------+
| 1 | Car | NULL | <-- Root (Top-Level Part)
| 2 | Engine | 1 | <-- Engine belongs to Car
| 3 | Wheel | 1 | <-- Wheel belongs to Car
| 4 | Piston | 2 | <-- Piston belongs to Engine
| 5 | Bolt | 4 | <-- Bolt belongs to Piston
+---------+------------+---------------+
</pre>
</section>

<section>
<h5>Recursive Self-JOIN with Levels</h5>
<pre><code>
WITH RECURSIVE CarParts AS (
-- Start with the whole car (top-level part)
SELECT t1.part_id, t1.name AS part_name,
t1.parent_part_id AS parent_id,
NULL AS parent_name, 1 AS level
FROM parts AS t1
WHERE t1.parent_part_id IS NULL

UNION ALL

-- Recursively join parts to their parent parts and track levels
SELECT t2.part_id, t2.name, t2.parent_part_id,
c.part_name AS parent_name, c.level + 1
FROM parts AS t2
JOIN CarParts AS c ON t2.parent_part_id = c.part_id
)
SELECT * FROM CarParts;
</code></pre>
</section>

<section>
<h5>Recursive Self-JOIN Output</h5>
<p>Querying the full car parts hierarchy using recursion.</p>
<pre><code>
+---------+------------+-----------+-------------+--------+
| part_id | part_name | parent_id | parent_name | level |
+---------+------------+-----------+-------------+--------+
| 1 | Car | NULL | NULL | 1 |
| 2 | Engine | 1 | Car | 2 |
| 3 | Wheel | 1 | Car | 2 |
| 4 | Piston | 2 | Engine | 3 |
| 5 | Bolt | 4 | Piston | 4 |
+---------+------------+-----------+-------------+--------+
</code></pre>
<p>🔁 Recursive query returns all levels of the hierarchy!</p>
</section>

<section>
<h5>Questions?</h5>
</section>

<section>
<h5>Project Part 1, Homework 3, Lab 3</h5>
</section>

<!-- Indexing Module 7 -->

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