Faculty of Science and TechnologyITECH1006/5006 Database Management Systems Database Management Systems Tutorial Week 2 Tasks 1. Identify issues in the Crow’s Foot notations used in the following ERD. “AUTHORS” should be “AUTHOR” – Entity name should be singular. “BOOK” should be “BOOK” – Entity name should be in uppercase. “IS WRITTEN BY” should be “writes” – Relationship name should be an active verb due to the positioning of the two entities. Notes: The main purpose of this task is to get students to discuss the good convention in ER modelling. Generally, the labelling/naming of the entities, attributes, and relationships must be consistent. Students should stick to one set of notations, instead of switching between different sets (e.g. Chen Crow’s Foot). In this course, we expect students to use the Crow’s Foot notations. 2. Lucidchart - this product is a browser based diagramming tool; it is able to draw a wide range of different diagrams, including ER Diagrams. As a University student you are entitled to a free Lucidchart account. You can sign up for the free account using your university email address. When your account is created and an invitation email sent to your FedUni student account (check Spam if the message is not in your inBox). Click on the link in your Lucidchart welcome email and you will be able to make use of the software. As a first step you should look at the provided tutorials, in particular "Entity Relationship Diagrams". To prepare conceptual models (ERDs), you may use Lucidchart or any other drawing package. Notes: The main purpose of this task is to expose students to an ER diagramming tool. In this course, although students can use any software (including simple ones like MS-Word) for creating their ERD, I believe it would be much easier and less tedious if students could using a proper diagramming tool. Note that it is not in the scope of this course to teach every aspect of Lucidchart and students are expected to explore the tool independently. CRICOS Provider No. 00103D ITECH 1006 / 5006 Laboratory 2 Page 1 of 6 3. Given a scenario represented by the following entities. customer number and for each product ordered the quantity ordered and the total line price PRODUCT . where customers place orders for products: CUSTOMER . address. phone number ORDER . Prepare the ERD shown above using your choice of drawing tool and then create a copy of this initial model and add all the non-primary key attributes listed in the scenario above to your copy. the use of foreign keys indicates that you are looking at a logical model where a choice has been made to use a relational database. product description and product unit price An initial ERD using Lucidchart for this scenario would be: This ERD only shows the primary keys of each of the entities. In such a complete ERD you must not show or label foreign keys. sometimes an ERD is drawn such that it will show all the non-primary key attributes for the model. name.order number. Solutions: CRICOS Provider No. 00103D ITECH 1006 / 5006 Laboratory 2 Page 2 of 6 . rather than a conceptual model.customer number.product number. order date. and each department is managed by one employee One of the employees runs each division. One of the employees manages each department. the above concepts of the relationships can be established. Some employees. Students should also note that business rules differ from organisations to organisations. While modelling. but each employee is employed by one department. students are expected to make logical assumptions. Use the above diagram and the business rules below. known as "rovers. create an Entity Relationship Diagram using Crow’s Foot notations." are not assigned to any department. students must understand that by deriving the business rules of an organisation. and each division is run by one employee. and a project may have many employees assigned to it.4. cardinalities and the participation on the relationships. if the rules are unclear. but each department is operated by one division An employee may be assigned to many projects. CRICOS Provider No. A division operates many departments. After completing this task. 00103D ITECH 1006 / 5006 Laboratory 2 Page 3 of 6 . o Include: all appropriate connectivities. all cardinalities and at least the minimum number of attributes required to implement the model o Business Rules: A department employs many employees. Solutions: Notes: The focus of this task is to get students to understand how to establish the connectivities. A project must have at least one employee assigned to it. DRIVER CAR One driver must drive at least one or more cars Assumptions: One car may be driven by zero or one driver.Notes: The purpose of Tasks 5 to 9 is to get students to practise ER modelling using the iterative modelling procedure taught in this course (see last slide for Learning Outcomes 5-7). Each team member belongs to zero to one project. 00103D ITECH 1006 / 5006 Laboratory 2 Page 4 of 6 . e. Acme Pty Ltd is made up of a number of departments that manage none or more projects. “car insurance company” are not modelled as an entity since we are modelling the data relationships in that company and information about itself is not relevant in that system. Solutions: CRICOS Provider No. students should understand how to establish if there is a relationship between two entities. 5. Each car has associated with it zero to many number of recorded accidents. Each team member belongs to one department. Each project is made up of none or more team members. students should understand when is a noun modelled as an entity and when as an attribute. They should also understand why some nouns are not modelled as entities or attributes. 6. in Task 5. Finally. When going through these tasks.g. One of the team members supervise the other team members on the project. Design an ER diagram for a car insurance company whose customers own one or more cars each. and • Instructors. year and teaching period. credits. Identify the entities and the attributes Solutions: 8. syllabus. including course number. Given the following business rules. the enrolment of students in courses and grades awarded to students in each course they are enrolled for must be appropriately modelled. • Course offerings. Document all assumptions that you have made Solutions: CRICOS Provider No. • Further. create an ER diagram for each of the specified relationships: • A company operates four departments • Each department employs staff • Each staff may work for one or more departments • A staff may be supervised by another staff • Each department has one manager. title. and title.7. including identification number. 00103D ITECH 1006 / 5006 Laboratory 2 Page 5 of 6 . instructors. and prerequisites. including course number. timings and classroom • Students. name. Design an ER diagram for university registrar including the following entities: • Courses. and program. name. including student-id. department. date.property. The date of payment. Tenants pay accounts to the Agency . tenant. contact address street. type of account (Rental.property. postcode & telephone number. An owner may own several properties.these consist of weekly rental payments. Properties are subject to damage and the agency records all instance of damage to its properties . The owner. property rented. property. Repair costs are charged directly to tenants Normal property maintenance is also noted . Prepare an Entity Relationship Diagram (ERD) showing all primary and non-primary key attributes for the following description of a Property Rental System: Properties are rented by tenants. Maintenance costs are charged to the property owner. Data held about tenants include family name. date.9. In addition the lease period and bond are recorded for each property or sub property rented. Each tenant is assigned a unique number by the Agency. Damage) and amount are recorded. state. a large shopping complex). Properties are owned by owners. address. Each property is assigned a unique building number. 00103D ITECH 1006 / 5006 Laboratory 2 Page 6 of 6 . The agency only recognises a single owner for any of the properties it handles. given name. A tenant may rent more than one property and many tenants may rent parts of the same property (eg. type of damage and repair cost are recorded. city. type of maintenance and cost are recorded. Solutions: CRICOS Provider No. bond payments (for new properties) and damage bills. Bond. and value are recorded for each property.