This ERD example model represents business entities of a DVD rental store using detailed physical ERD (for designing database schema ready for production). The DVD rental database has 15 data entities as shown in the ERD here.

The ERD example models the following scenario:

A salesperson may manage many other salespeople. A salesperson is managed by only one salespeople. A salesperson can be an agent for many customers. A customer is managed by one salespeople. A customer can place many orders. An order can be placed by one customer. An order lists many inventory items. An inventory item may be listed on many orders. An inventory item is assembled from many parts. A part may be assembled into many inventory items. Many employees assemble an inventory item from many parts. A supplier supplies many parts. A part may be supplied by many suppliers.

This ERD example shows a very simple database design of a video rental system by describing the customer, movies and the producers and the attributes and relationships between them

Production tracking is important in many manufacturing environments (e.g., the pharmaceuticals industry, children’s toys, etc.). The following ER diagram example captures important information in the tracking of production. Specifically, the ERD captures relationships between production lots (or batches), individual production units, and raw materials.

UPS prides itself on having up-to-date information on the processing and current location of each shipped item. To do this, UPS relies on a company-wide information system. Shipped items are the heart of the UPS product tracking information system. Shipped items can be characterized by item number (unique), weight, dimensions, insurance amount, destination, and final delivery date. Shipped items are received into the UPS system at a single retail center. Retail centers are characterized by their type, uniqueID, and address. Shipped items make their way to their destination via one or more standard UPS transportation events (i.e., flights, truck deliveries). These transportation events are characterized by a unique scheduleNumber, a type (e.g, flight, truck), and a deliveryRoute.

The ERD example captures this information about the UPS system. Be certain to indicate identifiers and cardinality constraints.

This is a simple ERD example for loan system.

Micro loans are small loans, which is beginning to gain popularity especially among borrowers in developing countries. The idea is to bring venture lenders together using information technology. Typically, the loans will be used to finance startup or development of the borrower’s company, so that there is a realistic chance for repayment. The money in a loan can, unlike traditional loans, come from many lenders. In this problem, you must create an E-R model that describes the information necessary to manage micro loans. The following information form the basis for creating the model:

• Each borrower and lender must be registered with information about name and address.
• A loan starts with a loan request, which contains information about when the loan should at latest be granted, The total amount being discussed (US-dollars), and how long the payback period is. Also, a description is included of how the money will be used. The rent on the payment is calculated in the loan amount, which is to say, the full amount is not paid .
• Lenders can commit to an optional portion of the total amount of a loan request.
• When the commitments for the loan request covers the requested amount, the request is converted to a loan. If not enough commitments can be reached, the loan request is cancelled. A borrower can have more than one request, and more than one loan at a time, but can at most make one request per day.
• The loan is paid through an “intermediary”, typically a local department of a charity, who has a name and an address.
• The borrower chooses when he or she will make a payment. Every payment must be registered in the database with an amount and a date (at most one payment per loan per day). The lenders share the repayment based on how large a part of the loan they are responsible for.
• If the loan is not repaid before the agreed upon deadline, a new date is agreed. The database must not delete the old deadline, but save the history (the deadline can be overridden multiple times).
• Each lender can for each burrower save a “trust”, which is a number between 0 and 100 that determines the lender’s evaluation of the risk of lending money to that person. The number must only be saved for the borrowers, for whom there has been made such an evaluation.

The academic world is an interesting example of international cooperation and exchange. This ERD example is concerned with modeling of a database that contains information on researchers, academic institutions, and collaborations among researchers. A researcher can either be employed as a professor or a lab assistant. There are three kinds of professors: Assistant, associate, and full professors. The following should be stored:

• For each researcher, his/her name, year of birth, and current position (if any).
• For each institution, its name, country, and inauguration year.
• For each institution, the names of its schools (e.g. School of Law, School of Business, School of Computer Science,. . .). A school belongs to exactly one institution.
• An employment history, including information on all employments (start and end date, position, and what school).
• Information about co-authorships, i.e., which researchers have co-authored a research paper. The titles of common research papers should also be stored.
• For each researcher, information on his/her highest degree (BSc, MSc or PhD), including who was the main supervisor, and at what school.
• For each professor, information on what research projects (title, start date, and end date) he/she is involved in, and the total amount of grant money for which he/she was the main applicant.

This ERD example models a simple order system with the following entities:

• Customer: stores customer’s data.
• Product: stores a list of scale model cars.
• ProductLine: stores a list of product line categories.
• Order: stores  sales orders placed by customers.
• OrderProduct: stores sales order line items for each sales order.
• Payment: stores payments made by customers based on their accounts.
• Employee: stores all employee information as well as the organization structure such as who reports to whom.
• Office: stores sales office data.

This ERD example shows the typical business entities of a college. A college contains many departments which can offer any number of courses. Many instructors can work in a department and an instructor can work only in one department. For each department there is a Head. An instructor can be head of only one department. Each instructor can take any number of courses, but course can be taken by only one instructor. A student can enrol for any number of courses and each course can have any number of students.