Database Schema Design

In line with the specifications you have given, here's a proposed database schema: **Entities:** 1. `Customers` 2. `Sales` **Database Schema:** **1. Customers** * CustomerID (Primary Key) * FirstName * LastName * Email (Unique Key) * Phone * Address * City * State * Zip * Country The `Customers` table will store customer's personal details. The `CustomerID` will be an auto-increment integer and act as the primary key. The `Email` field will be a unique key to prevent duplication of customer data. Other fields will store the necessary contact information. **2. Sales** * SaleID (Primary Key) * CustomerID (Foreign Key) * ProductID * Quantity * SaleDate * TotalPrice The `Sales` table will store all sales transaction data. `SaleID` will be the primary key, and `CustomerID` is the foreign key, creating a relationship with the `Customers` table. `ProductID` is assumed to link to a product table (not explicitly mentioned in the brief) and would store data about the product sold. `Quantity` and `SaleDate` will hold the number of units sold and the transaction date, respectively. The `TotalPrice` can be computed as quantity times the price of the product. **Relationship:** The relationship between `Customers` and `Sales` is one-to-many, which means that one customer can have multiple sales, but each sale is related to only one customer. This relationship is achieved through the `CustomerID` foreign key in the `Sales` table. **Access Needs and Security:** The sales team needs access to both customer and sales data. This can be managed through user permissions at the database level. We can set up specific roles (e.g., 'SalesRole') with access to `Customers` and `Sales` tables only, and the sales team members will be assigned this role. Furthermore, all customer data must be kept secure and confidential. Security measures could include encryption of sensitive data fields, periodic security audits, and strong access control mechanisms. We can also anonymize some of the customer data that sales team members have access to. For instance, we may choose not to disclose the full contact details of customers to the sales team. **Normalization:** This schema is in the 3rd Normal Form (3NF), which means there are no transitive dependencies, and each non-prime attribute is non-transitively dependent on every key of the table. It is crucial for avoiding redundancy and ensuring data integrity. Please note that this is a basic schema based on the information provided and might need further refinements depending on the business requirements, like handling returns, multiple addresses per customer, different sales status, etc.