Identify the necessary entities and their attributes for your database. Set appropriate. primary key for each entity accordingly.
Entity 1: Customers
- Attributes: customer_id (primary key), first_name, last_name, email, phone_number, address
Entity 2: Products
- Attributes: product_id (primary key), product_name, price, description, quantity_available
Entity 3: Orders
- Attributes: order_id (primary key), customer_id (foreign key referencing Customers entity), order_date, total_amount
Entity 4: Order Items
- Attributes: order_item_id (primary key), order_id (foreign key referencing Orders entity), product_id (foreign key referencing Products entity), quantity, item_total
Entity 5: Employees
- Attributes: employee_id (primary key), first_name, last_name, email, phone_number, address, position, hire_date
Entity 6: Categories
- Attributes: category_id (primary key), category_name
Entity 7: Reviews
- Attributes: review_id (primary key), customer_id (foreign key referencing Customers entity), product_id (foreign key referencing Products entity), rating, comment, review_date
To identify the necessary entities and their attributes for a database, you need to have a clear understanding of the domain or subject area you are designing the database for. Without that information, it is difficult to provide specific entities and attributes. However, I can provide a general approach for identifying entities and attributes:
1. Identify the main entities: These are the central or primary concepts in your database. For example, if you are designing a database for a university, the main entities may include students, courses, and instructors.
2. Identify attributes of each entity: Attributes represent the characteristics or properties of an entity. For example, attributes of a student entity may include student ID, name, date of birth, and contact details. For courses, attributes may include course ID, title, description, and credit hours.
3. Determine primary keys: A primary key is a unique identifier for each entity. It helps in uniquely identifying records in a table. Typically, the primary key is a single attribute or a combination of attributes that can uniquely identify each record. For example, in the student entity, the student ID attribute can be used as the primary key.
Here's an example using the university scenario mentioned earlier:
Entity: Student
- Attributes: Student ID (Primary Key), Name, Date of Birth, Contact Details
Entity: Course
- Attributes: Course ID (Primary Key), Title, Description, Credit Hours
Entity: Instructor
- Attributes: Instructor ID (Primary Key), Name, Contact Details
In this example, the primary keys are Student ID for the Student entity, Course ID for the Course entity, and Instructor ID for the Instructor entity.