Gain insights into fundamental database concepts, relational databases, and entity-relationship diagrams. Learn about normalization techniques and basics of SQL to enhance database efficiency.

Databases are universal - they underlie the technology you use every day. They're a crucial component of everything from telecommunications systems, banking systems, and video games to just about any other software system that maintains some amount of persistent data.

In this course, you'll learn about the fundamental concepts of databases, why and when they're used, what relational databases are, and entity-relationship diagrams. You will also be exposed to techniques like normalization that help to increase the efficiency of databases. You'll wrap up with a look at the basics of Structured Query Language (SQL). 

After completing this course, you will be able to move onto more advanced courses involving database systems and SQL.

Database Design Fundamentals for Software Engineers

## Solution

The second normal form states that it should meet all the rules for 1NF and there must be no partial dependencies between any of the columns with the primary key.

**Customer-order table**

| Cust_Id | Cust_Name | Order_Id | Order_Detail | Order_Category |
| --- | --- | --- | --- | --- |
| 1 | Jack | 34 | Shampoo | Hygiene |
| 2 | Bruce | 22 | TV | Electronics|
| 3 | Amanda | 84 | Shirts | Clothing |
| 4 | James | 12 | Shoes | Clothing |
| 2 | Bruce | 62 | Glasses | Clothing |
| 5 | Veronica | 84 | Shirts | Clothing |

First, we can see that the table above is in the first normal form; it obeys all the rules of the first normal form. 

Secondly, the primary key consists of the `Cust_Id` and the `Order_Id`. Combined, they are unique assuming the same customer would not order the same thing.

However, the table is not in the second normal form because there are partial dependencies of primary keys and columns. `Cust_Name` is dependent on `Cust_Id` and there's no real link between a customer's name and what he/she purchased. The `Order_Detail` and `Order_Category` are also dependent on the `Order_Id`, but they are not dependent on the `Cust_Id`, because there is no link between a `Cust_Id` and an `Order_Detail` or their `Order_Category`.

To make this table comply with the second normal form, you need to separate the columns into three tables.

First, create a table to store the customer details as shown below:

**Customer table**

| Cust_Id | Cust_Name | 
| --- | --- |
| 1 | Jack | 
| 2 | Bruce | 
| 3 | Amanda | 
| 4 | James | 
| 5 | Veronica | 

The next step is to create a table to store the details of each order:

**Orders table**

| Order_Id | Order_Detail | Order_Category |
| --- | --- | --- |
| 34 | Shampoo | Hygiene |
| 22 | TV | Electronics|
| 84 | Shirts | Clothing |
| 12 | Shoes | Clothing |
| 62 | Glasses | Clothing |


Finally, create a third table storing just the `Cust_Id` and the `Order_Id` to keep track of all the orders for a customer:

**Customer-order table**

| Cust_Id | Order_Id | 
| --- | --- | 
| 1 | 34 | 
| 2 | 22 | 
| 3 | 84 | 
| 4 | 12 | 
| 2 | 62 | 
| 5 | 84 | 

The third table is simply used to link the first two tables. 

Now all the tables are in 2NF as there is no partial dependency between any column.

# Solution

The second normal form states that it should meet all the rules for 1NF and there must be no partial dependencies between any of the columns with the primary key.

**Customer-order table**

| Cust_Id | Cust_Name | Order_Id | Order_Detail | Order_Category |
| --- | --- | --- | --- | --- |
| 1 | Jack | 34 | Shampoo | Hygiene |
| 2 | Bruce | 22 | TV | Electronics|
| 3 | Amanda | 84 | Shirts | Clothing |
| 4 | James | 12 | Shoes | Clothing |
| 2 | Bruce | 62 | Glasses | Clothing |
| 5 | Veronica | 84 | Shirts | Clothing |

First, we can see that the table above is in the first normal form; it obeys all the rules of the first normal form. 

Secondly, the primary key consists of the `Cust_Id` and the `Order_Id`. Combined, they are unique assuming the same customer would not order the same thing.

However, the table is not in the second normal form because there are partial dependencies of primary keys and columns. `Cust_Name` is dependent on `Cust_Id` and there's no real link between a customer's name and what he/she purchased. The `Order_Detail` and `Order_Category` are also dependent on the `Order_Id`, but they are not dependent on the `Cust_Id`, because there is no link between a `Cust_Id` and an `Order_Detail` or their `Order_Category`.

To make this table comply with the second normal form, you need to separate the columns into three tables.

First, create a table to store the customer details as shown below:

**Customer table**

| Cust_Id | Cust_Name | 
| --- | --- |
| 1 | Jack | 
| 2 | Bruce | 
| 3 | Amanda | 
| 4 | James | 
| 5 | Veronica | 

The next step is to create a table to store the details of each order:

**Orders table**

| Order_Id | Order_Detail | Order_Category |
| --- | --- | --- |
| 34 | Shampoo | Hygiene |
| 22 | TV | Electronics|
| 84 | Shirts | Clothing |
| 12 | Shoes | Clothing |
| 62 | Glasses | Clothing |


Finally, create a third table storing just the `Cust_Id` and the `Order_Id` to keep track of all the orders for a customer:

**Customer-order table**

| Cust_Id | Order_Id | 
| --- | --- | 
| 1 | 34 | 
| 2 | 22 | 
| 3 | 84 | 
| 4 | 12 | 
| 2 | 62 | 
| 5 | 84 | 

The third table is simply used to link the first two tables. 

Now all the tables are in 2NF as there is no partial dependency between any column.

In this lesson we will discuss the solution to exercise 1.

Introduction

Fundamental Concepts

Data Modeling

Entity-Relationship Data Model

The Relational Data Model

Functional Dependencies

Normalization

Structured Query Language

Conclusion

Solution to Exercise 1

Solution

Cust_Id	Cust_Name	Order_Id	Order_Detail	Order_Category
1	Jack	34	Shampoo	Hygiene
2	Bruce	22	TV	Electronics
3	Amanda	84	Shirts	Clothing
4	James	12	Shoes	Clothing