Based on the POS & Stock Controller system shown below, design an appropriate ER diagram that reflects the specified system and then extract the mapped tables showing them as flat tables.

A Point$-$of$-$Sale & Stock Controller System is an information system primarily used to monitor the sales and stock activities of a company.

In the POS & Stock Controller System it is possible to have the following entities:

Product

Product Category

Product Unit

Sales

Invoice

Receive Product

Customer

Supplier

Purchase Order

User

The possible relationships between them can be as follows:

The user determines the products $(1$ to N$).$

The user can handle multiple invoices $(1$ to N$).$

The user can manage the receiving transactions $(1$ to N$).$

The user can process the purchase order transactions $(1$ to N$).$

Product belongs to a certain category $($N to $1).$

Product has multiple product units $(1$ to N$).$

Product has multiple receiving transactions $(1$ to N$).$

Product is also included in the purchase order transaction $(1$ to N$).$

Purchase order will be forwarded to the supplier $(1$ N$).$

The supplier will supply the requested products $(1$ to N$).$

Product is included in multiple sales $(1$ to N$).$

Sales produce an invoice $(1$ to N$).$

An invoice is given to the customer $(1$ to N$).$

The last part of the ERD process is to add attributes to the entities as follows:

Product Entity has the following attributes:

Product ID $$ primary key represented with underline

Code

Name

Unit Price

Unit in Stock

Discount Percentage

Re$-$Ordervel

Category ID $$ foreign key

Unit ID $$ foreign key

User ID $$ foreign key

Product Category Entity has the following attributes:

Category ID $$ primary key represented with underline

Name

Product Unit Entity has the following attributes:

Unit ID $$ primary key represented with underline

Name

Sales Entity has the following attributes:

Sales ID $$ primary key represented with underline

Invoice ID $$ foreign key

Product ID $$ foreign key

Quantity

Unit Price

Sub Total

Invoice Entity has the following attributes:

Invoice ID $$ primary key represented with underline

Customer ID $$ foreign key

Total Amount

Amount Tendered

Payment Type

Bank Account Name

Bank Account Number

Date Recorded

User ID $$ foreign key

Receive Product Entity has the following attributes:

Receive Product ID $$ primary key represented with underline

Product ID $$ foreign key

Quantity

Unit Price

Sub Total

Received Date

Supplier ID $$ foreign key

User ID $$ foreign key

Customer Entity has the following attributes:

Customer ID $$ primary key represented with underline

Code

Name

Contact Address

Supplier Entity has the following attributes:

Supplier ID $$ primary key represented with underline

Code

Name

Contact

Email

Address

Purchase Order Entity has the following attributes:

Purchase Order ID $$ primary key represented with underline

Product ID $$ foreign key

Quantity

Unit Price

Sub Total

Order Date

Supplier ID $$ foreign key

User ID $$ foreign key

User Entity has the following attributes:

User ID $$ primary key represented with underline

Fullname $($FirstName$,$ MiddleName, LastName$)$

Contact

Designation

Account Type

Username

Password